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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Adventures in Converting my Precision Mathews Milling Machine to CNC
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  1. #21
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    May 2008
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    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by steelcogs View Post
    I've personally measured about .0015" of backlash on my X and Y and I believe I have an ArizonaVideo kit. (I bought it already converted so I can't remember 100% but it looks like his kit). Not sure whether or not it's double ballnut since I haven't taken it apart but I'd assume it's single.

    I have a Masso controller for my mill and for some hardware/software issue they currently have backlash comp disabled and it's eating away at me since I have a tendency to be a perfectionist with this sort of stuff lol.
    My older kits were single nuts and I re packed them for low backlash. .0015" would be a good result, better than some double nut kits. You have to remember that not all the backlash is from the ball nut. You will have a small amount from the end bearings, flex of the mounts, the coupler and stick slip. Getting under .001" is a bit hard even with a good tight ball nut.

    I see that the other guy from CNCelements says his kit is the shortest which is it not. His Y mount is short because he copied my arrangement and the X too.They would be almost exactly the same. My Y mount is a single piece so it a bit harder to make. It looks like this.

    Grizzly G0704 CNC Kit RM-16 C7 by arizonavideo | Photobucket

    If your Y looks like that then its my kit.

    Thanks guys

    Dave
    youtube videos of the G0704 under the name arizonavideo99

  2. #22
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    Jan 2018
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    1516

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by TCanndee View Post
    I am seeing about .002" in backlash. Y axis is .004 but I think I have a loose ballnut mount.

    I believe that you will get pretty close to the 200 mm you want on the y axis. My double ballnut was a bad idea. Working on a solution.

    I don't want to mention the brand online, but I was not impressed with the kit I used.
    0.004" (0.1mm) seems a lot. Flex of the screw beings 1 end is unsupported?
    I've got a double nut (China special) that seems not too great. The sleeve spins alone a bit.
    My plan at the mo is:
    1.To spacer pack between the 2 with tin foil until I get a tiny feel of friction.
    2. Spin the nut around so the sleeve faces the front end.
    3. Extend the slot on the base front and a little at the back.
    4. Make a nut mount that attaches/clamps to both the nut and sleeve and extra bolt point on the saddle.

    I'll be using just the cheap C7's for now. The only thing with those is the end machining isn't great for thrust bearing use I've felt.
    They can end up with a wobble because there's one point that doesn't contact well. You can end up with the screw moving up/down before the nut moves and this exaggerates into more backlash if only bearing supported at 1 end.

    I would like to drill through to the back so I can support the screw shaft at both ends for more rigidity but won't know until I get a good look at it.
    My column is top bolted too, apparently it's more rigid than the rear bolt ons used to be. This will determine how much I can extend the Y in that direction.

  3. #23
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    Sep 2018
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    15

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Hello gays l need help with spindle wont turn fanuc 6t-b.

    Sent from my SM-G355H using Tapatalk

  4. #24
    Join Date
    Mar 2009
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    27

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by TCanndee View Post
    The best solution I have found is a head spacer between the head and the z axis slide with the dovetail. I went with 2.5". I am also working on expanding the y axis travel an inch or so to the front by using a longer ballscrew, enlarging the hole through the front of the base to allow the ball nut through and an extended stepper mount. Hoping to achieve 7.5-8.5". On the G0704's people are also using a spacer to move the column back. This is much more complicated on the PM because the column mount is on top and not the back. I think this will give me the most travel that is practical.
    Thanks for the comments. The head spacer is probably the most common solution, but when you look at the movement of the saddle, it doesn't appear centered on the machined portion of the base. When moved toward the rear, the saddle doesn't reach the rear portion of the machined surface, but when you move it toward the front, it overhangs by maybe an inch and a half. Next time I take it apart, I'll confirm whether it's possible to add a new hole for the Y axis connection. It looks like it could be added about 1-3/8" forward of the existing hole, which would pretty much center the table. Of course then I'd have to make room by modifying the chip covers to allow the table to move back that far. Seems like the best option.

    Of course I've joked that you need a mill to be able to set up a mill, but sadly I don't have a spare.

    Rusty

  5. #25
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    Feb 2018
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    79

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by arizonavideo View Post
    My older kits were single nuts and I re packed them for low backlash. .0015" would be a good result, better than some double nut kits. You have to remember that not all the backlash is from the ball nut. You will have a small amount from the end bearings, flex of the mounts, the coupler and stick slip. Getting under .001" is a bit hard even with a good tight ball nut.

    I see that the other guy from CNCelements says his kit is the shortest which is it not. His Y mount is short because he copied my arrangement and the X too.They would be almost exactly the same. My Y mount is a single piece so it a bit harder to make. It looks like this.

    Grizzly G0704 CNC Kit RM-16 C7 by arizonavideo | Photobucket

    If your Y looks like that then its my kit.

    Thanks guys

    Dave
    Yep, looks like it's your kit then! Looks great btw! Hoping to be able to make parts that nice once I get my mill where I want it lol.

  6. #26
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    Apr 2018
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    9

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by arizonavideo View Post
    My older kits were single nuts and I re packed them for low backlash. .0015" would be a good result, better than some double nut kits. You have to remember that not all the backlash is from the ball nut. You will have a small amount from the end bearings, flex of the mounts, the coupler and stick slip. Getting under .001" is a bit hard even with a good tight ball nut.

    I see that the other guy from CNCelements says his kit is the shortest which is it not. His Y mount is short because he copied my arrangement and the X too.They would be almost exactly the same. My Y mount is a single piece so it a bit harder to make. It looks like this.

    Grizzly G0704 CNC Kit RM-16 C7 by arizonavideo | Photobucket

    If your Y looks like that then its my kit.

    Thanks guys

    Dave
    Dave,

    I have heard great things about your kits. I did try to find your kits when I started my conversion but was unable to find where to purchase. Do you still sell these kits for the PM-25MV? I'm afraid I got duped by the guy who made my kit for the PM-25MV. The double ball nuts are crap. To top it off he claimed that his kit required no saddle modification and it did. Then treated me like it was my fault when I called him on it. I feel really stupid spending the amount I did for something that is no better than a leadscrew. I just replaced the y axis screw to get more travel and really noticed a difference in the ballnuts and I didn't even buy anything special. Just an Amazon seller but they seem to be ok. I'll get to the backlash measurement tomorrow. Let me know about the kits. I may want to change everything out.

  7. #27
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    Feb 2018
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    79

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    TCanndee, I've heard that "no saddle modification" claims are kind of hit and miss. The guy I bought my mill from (Weiss VM25L, G0704 clone) said that they've done multiple conversions and between some of the mills that were supposed to be the same, some saddle modifications were sometimes needed and sometimes weren't.

  8. #28
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    Apr 2018
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    9

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    I spent some time working on the y axis travel and ended up with 8.5”. Had to cut out the slot in the base about 2”. Working on getting my spacer behind the head now. Had to order new bolts. The design from G0407.com called for the heads of the square head bolts to to be machined down to .575 and that is too small. I suspect this is a difference in the machines or they changed them over the years since. The bolt would have worked perfectly as is.

    still having issues with backlash. .004+ on all axis. I have pretty much narrowed it down to the bearings. Going to look into new bearing sets or change everything completely.

  9. #29
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    Jun 2018
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    36

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by TCanndee View Post

    still having issues with backlash. .004+ on all axis. I have pretty much narrowed it down to the bearings. Going to look into new bearing sets or change everything completely.
    Take a look at the CNCElements Conversion Kit. It's what I use on my machine. I'm very happy with how little backlash there is. It has special angular contact bearings. Some of the other kits don't use angular contact bearings in the bearing blocks to save on costs which causes all sorts of backlash issues.

  10. #30
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    Jun 2018
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    36

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by arizonavideo View Post
    I see that the other guy from CNCelements says his kit is the shortest which is it not. His Y mount is short because he copied my arrangement and the X too.They would be almost exactly the same. My Y mount is a single piece so it a bit harder to make. It looks like this.

    Grizzly G0704 CNC Kit RM-16 C7 by arizonavideo | Photobucket
    Dave,

    That is one beautiful conversion kit. You make it look easy.

    When comparing closely with the CNCElements kit, however, I see quite a number of differences in design/machining approach. The CNCElements kit actually uses two pieces on the Y mount. However, I definitely also see a lot of similarities. This makes sense since all conversion kits are constrained by the same machine, ballscrews, bearings, and NEMA 23/34 stepper motor geometries. You can take a closer look at pictures and video of the kit here:

    CNC Elements Conversion Kit

  11. #31
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    Apr 2018
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    9

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    just verified that my kit uses deep groove bearings. Not sure if I can just replace these with AC bearings or not. Does anyone have any insight?

  12. #32
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    Jun 2018
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    36

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by TCanndee View Post
    just verified that my kit uses deep groove bearings. Not sure if I can just replace these with AC bearings or not. Does anyone have any insight?
    It depends on how the bearing support block / mounting bracket was designed. For angular contact bearings to work, the bearing pocket needs to have two opposing faces for the bearings to seat against. This video has a good discussion on deep groove bearings vs angular contact bearings (starting at 1:00) and shows how angular contact bearings are installed correctly:

    https://www.youtube.com/watch?v=yWlOh71EW1s&t=4s

    Can you post a few pictures of what one of your bearing pockets look like on your machine with the stepper motor and bearings removed. It would probably be easiest to do this with the Y axis. Remove the stepper motor. Then undo the two bolts holding the Y axis stepper motor assembly to the base of the machine. Pull the table forward a couple of inches and undo the nut on the end of the ballscrew. The whole assembly should then come apart. It would also give you a good opportunity to see how loose the bearing races feel.

    I have some extra angular contact bearings lying around I would be happy to give you if they will work with your kit.

  13. #33
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    Apr 2018
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    9

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by CNCJoseph View Post
    It depends on how the bearing support block / mounting bracket was designed. For angular contact bearings to work, the bearing pocket needs to have two opposing faces for the bearings to seat against. This video has a good discussion on deep groove bearings vs angular contact bearings (starting at 1:00) and shows how angular contact bearings are installed correctly:

    https://www.youtube.com/watch?v=yWlOh71EW1s&t=4s

    Can you post a few pictures of what one of your bearing pockets look like on your machine with the stepper motor and bearings removed. It would probably be easiest to do this with the Y axis. Remove the stepper motor. Then undo the two bolts holding the Y axis stepper motor assembly to the base of the machine. Pull the table forward a couple of inches and undo the nut on the end of the ballscrew. The whole assembly should then come apart. It would also give you a good opportunity to see how loose the bearing races feel.

    I have some extra angular contact bearings lying around I would be happy to give you if they will work with your kit.
    CNCJoseph

    Thank you for your help. I don't have a small bearing puller at the moment. they are pressed into place. The housing is 25mm thick and the bearings are 9mm thick so there is a spacer. I did see these when I put them in. The bearings are 10x30x9. I have found some AC bearings that match these dimensions and the model is a 7200xxx. Having a little trouble finding an affordable sealed version but I have just started looking. All axis use the same bearing.

  14. #34
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    36

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by TCanndee View Post
    CNCJoseph

    Thank you for your help. I don't have a small bearing puller at the moment. they are pressed into place. The housing is 25mm thick and the bearings are 9mm thick so there is a spacer. I did see these when I put them in. The bearings are 10x30x9. I have found some AC bearings that match these dimensions and the model is a 7200xxx. Having a little trouble finding an affordable sealed version but I have just started looking. All axis use the same bearing.
    You're welcome. I'm afraid I don't have any that size.

    Sealed is definitely the way to go, but finding them is a challenge. If your bearings are relatively well protected by the nature of the conversion kit design, you could try unsealed bearings if you're comfortable with that idea.

  15. #35
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    Apr 2018
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    9

    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Hello. I finally got some AC bearings in and replaced the x axis bearings first. I now have well below .0005” backlash. Quite a difference from the .004 I was getting with the deep groove bearings my kit came with. Going to do a more accurate test once all the bearings are replaced.

    My kit kit was from Pro-Cut. I actually bought it through Automation Technologies along with an Acorn control stepper system. I would have to say that the DG ball bearings being used instead of AC bearings is a big turn off. That coupled with poor customer service and false advertising (kit was not supposed to require any machining on the saddle) is not good business practice. The control kit has been fine except it is crammed into a case that should be bigger. Very difficult to wire anything into the acorn or anything else. I almost forgot that when my controller came there were several things wired incorrectly according to centroid. I don’t recall what exactly it was but I didn’t bother even contacting them. I just fixed it. There are other issues with the kit as well. The y axis ball screw was too short to use the double ballnut as intended. I had to mount it backwards to get the 6.6” of travel I had. I have since replaced screw and nut in order to increase my travel to 8.5”.

    Anyway, just thought I’d throw a warning out about this kit.

    Dave at ArizonaVideo has been helping me out too. Very nice of him to offer me some bearings. I may still be replacing my whole kit with his.

  16. #36
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    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    I am a little miffed!?
    Just got round to un-crating my AMAT25LV and noticed the spindle center is nowhere near the table center.
    It's as though the head needs a spacer of about 1 inch thickness fitted.

    It has 185mm table movement on Y axis but with the column bellows fitted the distance between these and the spindle center is only 160mm.
    Couldn't get full 185 cut with them fitted when there's work on the table, only the 160mm is acheivable.

    With the bellows removed the spindle center measures 185mm distance from the dovetails, just.
    Also the table doesn't go all the way back (you can see the brass nut hit first) and hangs right out all the way to the handle when coming forward.
    With the table as far back as it goes there is still 40mm of the table left to go to the spindle center.
    With the table full forward the spindle center hangs right off it into empty space.

    Need to have a good look at this. Doesn't seem right at all.

  17. #37
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    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    I was wondering what AC bearings you guys were using? I've found some 7000 series that might work, but it's very hard to find the 7000RS to have the outer seal. If it's $10 more to get one with a seal,I'd rather do that instead of having to machine seals for them.

  18. #38
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    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by hackish View Post
    I was wondering what AC bearings you guys were using? I've found some 7000 series that might work, but it's very hard to find the 7000RS to have the outer seal. If it's $10 more to get one with a seal,I'd rather do that instead of having to machine seals for them.
    Won't be much help but my plan is:
    I'm looking to make my own bearing blocks with 32mm OD holes to take 7201 2RS bearings 12x32x10mm (Dunlop £10-11 each).
    Fitted to standard BK12 end machined C7 DFU1605 ballscrews.
    2 AC bearings at the motor end fitted back to back and a standard BF12 deep groove on the floating side. (on the X at least).
    Plan for the Y is similar if I have the available room to go straight through front to rear of the base with the screw.
    Only just looking at measuring the machine up.

    I'll be using some thrust bearings I already have for now until I get more funds as the DFU screws I ordered were more than I'd hoped.

    I don't mind using non sealed bearings as I do have a lot of zerk/grease point fittings lying around so I would just fit some onto the bearing blocks and keep them topped up.

    All depends on what fits if the plan with the 32mm OD fails miserably!


    ATM I'm trying to get my head round an issue that's puzzling me as mentioned in my comment below.
    My machine just seems to be crying out for the head to be extended out another at least 30mm with a spacer!?

  19. #39
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    Oct 2018
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    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Any pictures?

    IIRC I think it's 'normal' to have to move the bellows to achieve the travel and for the table to overhang a lot (only partially engaged in the dovetails) to get max forward travel. Basically you have travel similar to a bridgeport but the machine is much smaller and lighter, something has got to give...

    FYI I'm going to have a look at a Weiss '30' size machine on Friday I'll try to take some pics but I expect it's similar.

  20. #40
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    Re: Adventures in Converting my Precision Mathews Milling Machine to CNC

    Quote Originally Posted by men8ifr View Post
    Any pictures?

    IIRC I think it's 'normal' to have to move the bellows to achieve the travel and for the table to overhang a lot (only partially engaged in the dovetails) to get max forward travel. Basically you have travel similar to a bridgeport but the machine is much smaller and lighter, something has got to give...

    FYI I'm going to have a look at a Weiss '30' size machine on Friday I'll try to take some pics but I expect it's similar.
    V or LV? That has supposed Y of 210mm, correct?
    I'm sure I saw a measurement showing the spindle centre at 200mm distance from the bellows on the 30 size. So it will be similar but at least it should reach 190mm out of the box and then 210-220 with the bellows removed.
    180mm was what I was needing and would've gone for a 30LV if I'd known about the Y travel 'issue' on these stupid things

    Got a good mind to re-box it, get them to pick it back up on the basis that 'advertised perimeters can't be met without modification' ie: taking half of it apart. Then pay the extra to swap it for a 30LV instead.
    I have emailed them about this but had no response yet (go figure).

    Kinda have to go with this though I reckon & modify it because the space I have isn't wide enough for the bigger one. So frustrated atm.

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