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started my cnc conversion for Precision Matthews PM-25MV Mill
Hi,
I started my cnc conversion, I machine all the mounts now I need to order my ball screws next, here is one of many video's i posted look at this one or all Thanks, please let me know or recommend/ helpful tips I should know for this is my first cnc mill conversion and any help i would appreciate it!
Thanks
https://www.youtube.com/watch?v=xCGt8fY1hwM
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
I suggest to not machine parts untill you have the purchased components in your hands and verify dimensions first.
Especiallly if you buy cheap chinese components, dimensions might be out of tolerance.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
you have a good point, this is a proven plans and why i did it this way, if i ever do this again i will purchased the components first
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Those like really nice!
Are you using FK10/FK12 bearing cartridges by the looks of it?
I'm going down the same route, though I bought all of my electronics/motors/software so far, ballscrews came in today, and my FK bearings plus couplers are a month or so out yet on the slow boat from china, so I haven't started machining anything for the conversion yet.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
BrianPM
Those like really nice!
Are you using FK10/FK12 bearing cartridges by the looks of it?
I'm going down the same route, though I bought all of my electronics/motors/software so far, ballscrews came in today, and my FK bearings plus couplers are a month or so out yet on the slow boat from china, so I haven't started machining anything for the conversion yet.
I'm 3/4 the way through converting one myself using my X2 to make the parts.
I made my own bearing blocks to accommodate 32x12x10mm 7201-2RS Angular contact bearings for my 1605 screws.
Seeing how well they work I wouldn't go back to anything else.
I've packed my double nuts with some aluminium foil to make them tighter (they do now have a little drag). I've only got my Y axis properly set up atm but with the packed nuts and AC bearing combination my backlash has shown >0.001" (0.02mm).
Once this is finished I'll use it to change my X2 from thrust to AC bearings.
I went with 1100oz Nema 34 motors so added extra fixing points to the base and table for the bearing mounts. A fair amount of weight comes with those 34 size motors!
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
hey brain,
yes i when with FK/FF10 and 12 they have Angular contact bearings/ who did you buy your ballscrews from?
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Quote:
Originally Posted by
rmachinist
hey brain,
yes i when with FK/FF10 and 12 they have Angular contact bearings/ who did you buy your ballscrews from?
https://www.ebay.com/itm/PM-25MV-cnc-conversion-kit-precision-matthews-balls-crews-machined-as-drawings-/253926681285
They took about a week to get in from China, which was faster than I expected.
I’m still waiting for couplers and bearings.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
BrianPM
https://www.ebay.com/itm/PM-25MV-cnc-conversion-kit-precision-matthews-balls-crews-machined-as-drawings-/253926681285
They took about a week to get in from China, which was faster than I expected.
I’m still waiting for couplers and bearings.
Nice. I may have gone that route if I'd noticed them.
I've over complicated mine due to the pre made sizes I could get at the time. Gone DFU1605 all round.
Having grief getting my Y axis gib set correctly due to being like a slight banana. Tight when fully engaged but once it goes forward and saddle over hangs it goes loose and saddle is twist able (wobbles).
Any suggestions?
Daz.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
BrianPM
https://www.ebay.com/itm/PM-25MV-cnc-conversion-kit-precision-matthews-balls-crews-machined-as-drawings-/253926681285
They took about a week to get in from China, which was faster than I expected.
I’m still waiting for couplers and bearings.
I bought the same one 3 days ago! a week thats fast! let me ask i'm still waiting on a tracking number did chai provide one and what mail carrier did he use?
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
IIRC, it was DHL, and there was a tracking number.
ETA: I just checked my records... I ordered on the evening of 5/31, received the screws on 6/11, and was contacted by DHL with tracking info on 6/8.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
How was the quality on your PM25? I am in the middle of my conversion on the 30MV. The biggest issue was when I moved any of the axis before I tore it down there was a horrible grinding noise from the grease being loaded with sand, I am guessing from the castings. Also I received it half the screws were loose including the largest one holding the column on. I will a little shocked when I was able to remove two of the 4 bolts by hand. All the lead screw except the y axis had powder coat on them along with a couple of the mating surfaces. One of my Z axis bearing was missing a ball. I am just unlucky or do I need to lower my expectations? I know for the price one can't expect perfection but from all the review I read I was expecting a bit better then what I got. I also have a lathe from them inbound on the slow boat and I am a bit concerned. Should I just plan on doing a full tear down on that as well to get everything cleaned up? I know there is no way I would have ran this mill out of the box.
I have everything for my conversion sitting in the corner taunting me. I don't want to cut into the base until I get the conversion kit. David and ArizonaVideo is diligently working on them and I think it should ship this week.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
sundewzer
How was the quality on your PM25? I am in the middle of my conversion on the 30MV. The biggest issue was when I moved any of the axis before I tore it down there was a horrible grinding noise from the grease being loaded with sand, I am guessing from the castings. Also I received it half the screws were loose including the largest one holding the column on. I will a little shocked when I was able to remove two of the 4 bolts by hand. All the lead screw except the y axis had powder coat on them along with a couple of the mating surfaces. One of my Z axis bearing was missing a ball. I am just unlucky or do I need to lower my expectations? I know for the price one can't expect perfection but from all the review I read I was expecting a bit better then what I got. I also have a lathe from them inbound on the slow boat and I am a bit concerned. Should I just plan on doing a full tear down on that as well to get everything cleaned up? I know there is no way I would have ran this mill out of the box.
I have everything for my conversion sitting in the corner taunting me. I don't want to cut into the base until I get the conversion kit. David and ArizonaVideo is diligently working on them and I think it should ship this week.
The only issue I had with my PM-25MV was that I had to add 0.004" of shim stock into the bottom front of the column to get the y-axis to tram correctly and the Z-axis square to the table- its not perfect still, but a thou over the travel of the y-axis is good enough for my needs right now. The bolts holding the head weren't super tight, but I had to loosen them for tramming anyway. Other than that, its just cosmetic stuff, but I didn't buy it for the looks..
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
sundewzer
How was the quality on your PM25? I am in the middle of my conversion on the 30MV. The biggest issue was when I moved any of the axis before I tore it down there was a horrible grinding noise from the grease being loaded with sand, I am guessing from the castings. Also I received it half the screws were loose including the largest one holding the column on. I will a little shocked when I was able to remove two of the 4 bolts by hand. All the lead screw except the y axis had powder coat on them along with a couple of the mating surfaces. One of my Z axis bearing was missing a ball. I am just unlucky or do I need to lower my expectations? I know for the price one can't expect perfection but from all the review I read I was expecting a bit better then what I got. I also have a lathe from them inbound on the slow boat and I am a bit concerned. Should I just plan on doing a full tear down on that as well to get everything cleaned up? I know there is no way I would have ran this mill out of the box.
I have everything for my conversion sitting in the corner taunting me. I don't want to cut into the base until I get the conversion kit. David and ArizonaVideo is diligently working on them and I think it should ship this week.
when I gotten my pm25mv I wasn't too happy with their quality neither I complain about it little to Precision Matthews for the money I spent on it, I was expecting something little nicer. It’s a must doing a full tear down to get everything cleaned up and adjusted again, I feel like I shouldn’t had to gone thru this , but ½ a day later once done very thing worked out great, , Don’t buy the stand! The stand looks nice but I had problems with mind it rocking around on the floor I have a new house and the mill is in the basement I didn’t want to drill holes in the new floor, I ended up buying square steel tubing and leveling caster now it’s lot more solid, I think making a stand or buy a tool box would be lot better option, I also read the reviews before buying and comparing mills I’m happy I chosen Precision Matthews in my opinion I believe there better than others out there
I made all of my parts at work/ I just received my ball screw from chia I’m getting close I need motors and few more smaller stuff
like to see pictures of your mill and after the conversion , what are you going to put your electronics in?
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
BrianPM
IIRC, it was DHL, and there was a tracking number.
ETA: I just checked my records... I ordered on the evening of 5/31, received the screws on 6/11, and was contacted by DHL with tracking info on 6/8.
hi brain, i just received my ball screws today can you do me a favor check your lengths on them and make sure there right and let me know? mind seem a bit long
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
I have 750mm on X, 350mm on Y, and 600mm on Z. Z can be a bit longer with no problem.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
arizonavideo
Yes, working on them
GREAT! Thank again for all the information and helping me pick the motors.
Quote:
Originally Posted by
BrianPM
The only issue I had with my PM-25MV was that I had to add 0.004" of shim stock into the bottom front of the column to get the y-axis to tram correctly and the Z-axis square to the table- its not perfect still, but a thou over the travel of the y-axis is good enough for my needs right now. The bolts holding the head weren't super tight, but I had to loosen them for tramming anyway. Other than that, its just cosmetic stuff, but I didn't buy it for the looks..
I didn't buy it for the looks either, if I did would have went the a Grizzly. Just can't beat that forest service green ;) . What I did buy it for was moving the table and head. These thing are really hard to do when bearing are missing balls and bearing are packed with rust not oil.
https://photos.app.goo.gl/WmP2Xb7j1hoFuVEK6
This just tells me that they have no quality control in the states. It was hard to turn the handle and the noise was awful. On the flip side all of the mating surfaces look great, that is once I got all the powercoat of them.
Quote:
Originally Posted by
rmachinist
Don’t buy the stand! The stand looks nice but I had problems with mind it rocking around on the floor I have a new house and the mill is in the basement I didn’t want to drill holes in the new floor, I ended up buying square steel tubing and leveling caster now it’s lot more solid, I think making a stand or buy a tool box would be lot better option, I also read the reviews before buying and comparing mills I’m happy I chosen Precision Matthews in my opinion I believe there better than others out there
I made all of my parts at work/ I just received my ball screw from chia I’m getting close I need motors and few more smaller stuff
like to see pictures of your mill and after the conversion , what are you going to put your electronics in?
I am putting mine on a toolbox from Harbor Freight. I am guessing I will have to reinforce it. I went a bit overkill on the motors and went with all NEMA 34 Cleapath motors (CPM-SDSK-3421S-RLS). When I priced it out it was about $100 more than the DMM Servos and I got bigger motors that are all the same. Plus I have used Clearpath in the past and there customer support is next to none. I will using UCCNC with the UC300ETH-UB1 from CNCRoom. To answer you question, I don't know yet. I plan on 3D printing something but I am going to wait until I have it all setup to decided the best spot. The other really nice thing about the clearpath motors is I don't need a large enclosure because the controller are on the motors. All I have is the UC300ETH-UB1 and the power supply which I want in the open for cooling, probably on the back of the mill or toolbox.
Here is the album for all the picture that I will keep adding to if anyone is interest.
https://photos.app.goo.gl/ujsUpkb9SF3Q1r8Z7
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
shooter123456
I have 750mm on X, 350mm on Y, and 600mm on Z. Z can be a bit longer with no problem.
I ended up with DFU screws of 800mm on X- made a thicker block for floating end. Cut down a 450mm on Y to fit- unsure on exact size. 650mm on Z to allow for my dual single nut design.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
sundewzer
I am putting mine on a toolbox from Harbor Freight. I am guessing I will have to reinforce it. I went a bit overkill on the motors and went with all NEMA 34 Cleapath motors (CPM-SDSK-3421S-RLS). When I priced it out it was about $100 more than the DMM Servos and I got bigger motors that are all the same. Plus I have used Clearpath in the past and there customer support is next to none. I will using UCCNC with the UC300ETH-UB1 from CNCRoom. To answer you question, I don't know yet. I plan on 3D printing something but I am going to wait until I have it all setup to decided the best spot. The other really nice thing about the clearpath motors is I don't need a large enclosure because the controller are on the motors. All I have is the UC300ETH-UB1 and the power supply which I want in the open for cooling, probably on the back of the mill or toolbox.
Here is the album for all the picture that I will keep adding to if anyone is interest.
https://photos.app.goo.gl/ujsUpkb9SF3Q1r8Z7
I've gone Nema34 as well.
For peace of mind really. Allows the gibs to be a little tighter than when using Nema23.
Must admit though there is a bit of weight there on the X table end.
Would you add something on the other end to balance it a bit?
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
dazp1976
I've gone Nema34 as well.
For peace of mind really. Allows the gibs to be a little tighter than when using Nema23.
Must admit though there is a bit of weight there on the X table end.
Would you add something on the other end to balance it a bit?
The clearpath motor are only 4lbs and less than 4" long. I don't think a counter weight is required. If something was needed I would just shift the workpiece closer to the side with the motor on it so you have more overhang on the opposite side.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
sundewzer
The clearpath motor are only 4lbs and less than 4" long. I don't think a counter weight is required. If something was needed I would just shift the workpiece closer to the side with the motor on it so you have more overhang on the opposite side.
I'll do that for now and see how it goes.
Motor + bearing carriers weigh in just shy of 4kg on mine (8.5lb ish).
My slow progress here:
https://www.cnczone.com/forums/bench...m25-clone.html
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
dazp1976
wow your doing a great job!
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
shooter123456
I have 750mm on X, 350mm on Y, and 600mm on Z. Z can be a bit longer with no problem.
yea my Z is about .200 longer
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
If you get your X axis adjusted correctly the weight of the servo/stepper and hardware is absolutely inconsequential. For example, I tighten my ways until the X stalls, but I do that with two 4" vises and a 6" 3 jaw chuck at the end of the table at maximum overhang. I then take off the 6" chuck and generally the table runs freely. The two vises and the chuck are like 70lbs worth of weight. Even if I machine with two vises they are never at the end of the table, alway near middle, maybe slightly offset right to account for my tool height touch off on the left. Suffice it to say, this test shows how insensitive your table should be to weight changes.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
sundewzer
I didn't buy it for the looks either, if I did would have went the a Grizzly. Just can't beat that forest service green ;) . What I did buy it for was moving the table and head. These thing are really hard to do when bearing are missing balls and bearing are packed with rust not oil.
https://photos.app.goo.gl/WmP2Xb7j1hoFuVEK6
This just tells me that they have no quality control in the states. It was hard to turn the handle and the noise was awful. On the flip side all of the mating surfaces look great, that is once I got all the powercoat of them.
Did you call or contact their customer service? I have a feeling that they would make it right for you.
I actually contacted them because I had ordered a set of end mills with my machine and couldn't find them. They replied very promptly and told me where they should have been attached to the crate. I simply didn't find them in the first look because I had my son uncrate the machine while I was at work...
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
I didn't check my ballscrew lengths, only tested the ends to make sure they fit the bearings and preload nuts correctly. I'm just starting to machine the conversion parts now.
If Z or Y are too long, I figure I could cut/grind them down.
X- I can make my motor standoff a little taller.
I'm taking a shortcut with the motor standoffs to save a lot of time since I'm doing all the cutting manually.
I ordered these for the x and y mounts, they are a little tall, so I should just need to cut them down to the proper height. https://www.amazon.com/RATTMMOTOR-St...gateway&sr=8-6
I ordered a Nema34 mount as well, but its design is different (hollow) and I thought I would have to do significant modifications to get it to work, so I sent it back. Turning the standoffs on a lathe would be a lot easier in this case.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
BrianPM
Did you call or contact their customer service? I have a feeling that they would make it right for you.
I actually contacted them because I had ordered a set of end mills with my machine and couldn't find them. They replied very promptly and told me where they should have been attached to the crate. I simply didn't find them in the first look because I had my son uncrate the machine while I was at work...
I did and they are sending new bearing. Their customer service is great. It is their quality control that is lacking. I understand not catching the bearing that was missing a ball on the Z, it was barely noticeable. The rusted one however was as obvious as a slap in the face with one turn of the handel. But I guess you can't catch everything. For all the other stuff they told me to if I don't want to deal with it spend more money and get the Ultra Precision model. You get what you pay for.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
dazp1976
I love the enclosure! That is way more industrial than my plans. All you need now is a chip auger ;)
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
what size of OZ stepper motors should i go on the pm25mv?
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
I was using 400 oz in steppers on X and Y, and a 1200 on the Z (though that was way overkill for the Z).
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
rmachinist
what size of OZ stepper motors should i go on the pm25mv?
What I did for an estimate on for the 30MV was take my hardest material to cut, SS 304 for me, and guessed at my the toughest cut. I used https://fswizard.com/www/ to get some rough numbers and if you click the blue bar on top you get cutting force. I am not sure if it is radial and axial combined but I assumed worst case it was all radial, came out to about 180#.
Put that in a lead screw calculator. https://www.amesweb.info/Screws/Lead...meThreads.aspx and got about 800 oz in.
I knew I wanted Teknic Clearpath SDSK motors so my choice was easy and went with 1100 oz in on all 3 axis knowing that my X and Y are overpowered for 80% of my jobs. I am sure the 640 oz in would have been find but it was $20 more for the bigger motor and I am a sucker for a cheap upgrade.
I am sure this isn't the best method and I would love to hear what others have done to size their motors.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
I just went with typical recommendations for the G0704 machines: 570s on the X&Y and a 906 on the Z- I was going to use a 570 on the Z as well, but I wasn't sure if it would be enough as this is my first machine. I don't have anything put together yet, so I can't comment on how well they work.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
sundewzer
What I did for an estimate on for the 30MV was take my hardest material to cut, SS 304 for me, and guessed at my the toughest cut. I used
https://fswizard.com/www/ to get some rough numbers and if you click the blue bar on top you get cutting force. I am not sure if it is radial and axial combined but I assumed worst case it was all radial, came out to about 180#.
Put that in a lead screw calculator.
https://www.amesweb.info/Screws/Lead...meThreads.aspx and got about 800 oz in.
I knew I wanted Teknic Clearpath SDSK motors so my choice was easy and went with 1100 oz in on all 3 axis knowing that my X and Y are overpowered for 80% of my jobs. I am sure the 640 oz in would have been find but it was $20 more for the bigger motor and I am a sucker for a cheap upgrade.
I am sure this isn't the best method and I would love to hear what others have done to size their motors.
That link is for calculating the force produced by an ACME screw. The OP has ballscrews which are much more efficient. Here is a calculator for ballscrews. For efficiency, a ballscrew is about 90% efficient.
My G0704 has the 570 oz-in steppers on all axes and has proven sufficient in X and Y but I would like a bit more on Z due to drilling forces. The ballscrew calculator says a 570 oz-in motor on a 0.196" (5mm) lead screw at 90% efficiency will give 1027 pounds of linear force. Using your 180 pound cutting force requirement there is a healthy margin. However, for a stepper design, the desired rapid speed may be the driver for motor sizing. This is because stepper torque drops off with increasing RPM and there will be a speed where the stepper will stall. For the 570 oz-in motors I can rapid reliably at about 150 IPM with double spring preload ball nuts. With single ball nuts that speed is closer to 200 IPM
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
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its my understanding that you shim between the ballnuts to create preload when the holes are aligned. The z-axis already comes that way- shimmed in between and attached by the ‘ears’ for this purpose.
My y-axis came in timed just like yours and my x-axis was pretty close too. I had planned to cut some disks matching the flanges from shim stock.
The timing on your X-axis looks off by quite a bit, not being sure of the geometry and just spitballing.... but I wonder if the orientation of the 2 ballnuts were reversed, if they would line up closer? The other option might be to turn a spacer to put between them.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
[QUOTE=rmachinist;2305394]Here are the ball screws I just received /QUOTE]
The plastic tubes are for removing the nuts without losing any bearings, carefully. put sleeve on end that's not threaded and wind the nut onto it.
Imo I'd be happy with the Z but not the X,Y. I'd expect them all to look like the Z.
With the Y, shim between the 2 nuts as needed (I find alu foil good for this, I have some that is 0.01mm thickness) however I haven't had much luck getting mashed together nuts working that well. Having said that it was on my Z which has limited space for making adjustments anyway..
With the X, what I would consider is removing a nut, putting the mounting block on, replacing the nut so the mount is between the 2, that's if you have threaded holes on both sides of the block. This will aid the shimming process because they are so far out as-is. This way you can skim the block down if you need to to get them close to flush as you can which will then lessen the amount of shimming required. But... doing this may mean you have the annoyance of constantly needing to remove the nut as you make the adjustment. Is the best plan imo though.
Those grease nipples are a bit of a laugh too. How do you expect to get a grease gun on the Z nut when it's fitted???. You want some elbow fittings and 4mm tubing so you can put the grease nipples on the outside of the machine. Grease then flows from the nipple, through the tube, into the nut.
Unless you're doing a one shot oil system.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
109jb
That link is for calculating the force produced by an ACME screw. The OP has ballscrews which are much more efficient. Here is a calculator for ballscrews. For efficiency, a ballscrew is about 90% efficient.
My G0704 has the 570 oz-in steppers on all axes and has proven sufficient in X and Y but I would like a bit more on Z due to drilling forces. The ballscrew calculator says a 570 oz-in motor on a 0.196" (5mm) lead screw at 90% efficiency will give 1027 pounds of linear force. Using your 180 pound cutting force requirement there is a healthy margin. However, for a stepper design, the desired rapid speed may be the driver for motor sizing. This is because stepper torque drops off with increasing RPM and there will be a speed where the stepper will stall. For the 570 oz-in motors I can rapid reliably at about 150 IPM with double spring preload ball nuts. With single ball nuts that speed is closer to 200 IPM
You are correct on the calculator, I should have spend the extra couple minutes to find for specific for ball screws. I just changed the coefficient of friction 0.01.
Going from a single ball nut to a double you have to decrease your rapid speed by 25%? Is that typical?
Quote:
Originally Posted by
rmachinist
Here are the ball screws I just received
Getting exciting now! I would get some steel shim stock to put between the nuts but I guess the aluminum foil would work in a pinch. I have also read about people adding spring washers between them but you have to make sure your preload is greater than your cutting force.
Have you decided on the type of motors yet? I know I will never buy anything with just steppers again. I have had lots of fun with my shapeoko, including cutting the base of the 30MV https://photos.app.goo.gl/RBULexURfKht1DuTA, but I lost to many parts due to a missed step. If you can afford it I would go with some sort of closed loop system.
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Those grease nipples are a bit of a laugh too. How do you expect to get a grease gun on the Z nut when it's fitted???. You want some elbow fittings and 4mm tubing so you can put the grease nipples on the outside of the machine. Grease then flows from the nipple, through the tube, into the nut.
Unless you're doing a one shot oil system.[/QUOTE]
dazp1976,
i was thinking the same thing where did you buy your elbow fittings? you have a part numbers?
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Originally Posted by
sundewzer
You are correct on the calculator, I should have spend the extra couple minutes to find for specific for ball screws. I just changed the coefficient of friction 0.01.
Going from a single ball nut to a double you have to decrease your rapid speed by 25%? Is that typical?
Getting exciting now! I would get some steel shim stock to put between the nuts but I guess the aluminum foil would work in a pinch. I have also read about people adding spring washers between them but you have to make sure your preload is greater than your cutting force.
Have you decided on the type of motors yet? I know I will never buy anything with just steppers again. I have had lots of fun with my shapeoko, including cutting the base of the 30MV
https://photos.app.goo.gl/RBULexURfKht1DuTA, but I lost to many parts due to a missed step. If you can afford it I would go with some sort of closed loop system.
Going to try to get close loop steppers
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Re: started my cnc conversion for Precision Matthews PM-25MV Mill
Quote:
Going from a single ball nut to a double you have to decrease your rapid speed by 25%? Is that typical?
This is because my ballnut setup uses springs to force the ballnuts apart resulting in absolutely no backlash. The spring force is about 100-150 pounds driving them apart. On most double nut setups the ballnuts have shims between them to provide as little backlash as possible without binding, but because of screw lead errors the shimming cannot eliminate the backlash without binding the screw at some locations, so this method usually still has a little bit of backlash. Not much, but still a bit.
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Have you decided on the type of motors yet? I know I will never buy anything with just steppers again. I have had lots of fun with my shapeoko, including cutting the base of the 30MV
https://photos.app.goo.gl/RBULexURfKht1DuTA, but I lost to many parts due to a missed step. If you can afford it I would go with some sort of closed loop system.
I too would recommend some type of closed loop system if the budget allows. On my new build I am using closed loop steppers and they seem great for my expectations. I had originally planned to use servos because I wanted some type of following error detection, but I opted for the closed loop steppers as providing all the performance I really needed, easier setup than most servos, direct drive, and the following error detection. It was also a little cheaper too.
Having said that, I am still using and will continue to use open loop on other things because the closed loop stuff is quite a bit more expensive. On my G0704 I have not had any problems with losing steps as long as I don't push the machine too hard. It really comes down to a cost-benefit analysis that only you can do.