[tauscnc]

Hey Cbass,

I am sorry to hear you returned your machine but glad to hear you got your refund. That is good customer service (I assume all went well with the return).

What type of things are you trying to cut with .001 tolerance (0.0254 mm). With any machine won't the cutters deflect that much? I wonder if my machine has that type of bend in the middle. I rest my machine with the spindle in the corner as to decrease the chances of that deflection or take off the router as to decrease the weight.

Keep us posted on what you get.

Later buddy,

taus
www.cuttingedgecnc.com

[cbass]

Hey Cbass,

I am sorry to hear you returned your machine but glad to hear you got your refund. That is good customer service (I assume all went well with the return).

What type of things are you trying to cut with .001 tolerance (0.0254 mm). With any machine won't the cutters deflect that much? I wonder if my machine has that type of bend in the middle. I rest my machine with the spindle in the corner as to decrease the chances of that deflection or take off the router as to decrease the weight.

Keep us posted on what you get.

Later buddy,

taus
www.cuttingedgecnc.com

Hey Taus,

I'll be milling a variety of materials (plastics, aluminum, ceramics). I'm making sculptural objects, so I don't want to have to hand sand my surfaces. I want them to look perfect and flat. The bowed table is an issue for me because I want to be able to mill surfaces flat and then stack them like a sandwich in whatever order I wish. Any deviation from flat will result in a curved gap.

I'm getting closer to knowing what I need at this point.

I will still follow this thread closely.

Thanks,

Carlo

[sploo]

Hey Taus,

I'll be milling a variety of materials (plastics, aluminum, ceramics). I'm making sculptural objects, so I don't want to have to hand sand my surfaces. I want them to look perfect and flat. The bowed table is an issue for me because I want to be able to mill surfaces flat and then stack them like a sandwich in whatever order I wish. Any deviation from flat will result in a curved gap.

I'm still considering a K2 machine, for an application that's not too different from what you want. Surely, as Arch points out, you could put a tabletop on the machine and mill it 'flat'. I've heard of at least two others doing this (not just on K2 machines) so it must work to some degree?

I've noticed that quite a few people on this forum now have 3925's, but keeping track of what everyone's got isn't easy. Having scanned quite a few posts, I've managed to arrive at the following (upgrades, max speeds etc.):

AeroJDK: servos, 75ipm (more now?), happy
Akess: servos, 200ipm
Arch: rails on Z, upgraded ballscrews on all axes, 200ipm, servos, happy
carlnpa: upgraded ballscrews (later), happy
cbass: ballscrew probs, machine returned
CNCRob: servos, 75ipm, fairly happy
tauscnc: steppers, generally happy, ballscrews could be better
zealouse: rails on Z, upgraded ballscrews on all axes, servos, happy

I'd be grateful if people could correct any mistakes I've made, and fill in the blanks.

It seems to me that the two who are happiest with their machines (Arch and zealouse) ticked all the boxes (upgraded Z axis, and ballscrews all round). Maybe that's the key to getting a good machine?

[cbass]

Hey Sploo,

The issue I had with doing this was that if the rails are flat and are mounted to a curved rail, when you put a surface over the top, two things can happen:

1-Tabe top will straighten the aluminum extrusion, and bend the rails. This would not be a good thing! Even if you mill your table in place, it will only be as flat as the curved rails.

2-Table top will conform to bent aluminum extrusion. Rails will remain straight. This is more ideal as far as the linear quality of movement is concerned.

This wasn't something I was willing to risk. Beyond this, I wasn't able to lay a flat table on the extrusions because the middle support was skewed. Ask them if you can get the Non-Skewed version.


As for the upgrades, I'd say its money well spent as opposed to having to upgrade latter. Just my $.02.

Carlo

[tauscnc]

Hey Sploo,

I think you got mine pretty good. Overall I like the machine, the working size, etc. I also like the Z axis height. The more I play with it the more I see where little things could be improved, but that goes with probably most thing we get. Mostly, get the better ballscrews/nuts and get the upgraded Z axis. They did not have the upgraded ballscrews or did not mention them to me back then but luckily I did get the upgraded Z. I think this would make my machine even nicer. I also think the rails that support the long axis (39" one) are rather small. A 1" by 3" would fit there also (1030 rail) or a 1530 rail would too. I am still thinking of doubling mine with another 1020 rail and probably will. The stepper motors work well on my machine for the most part.

If I was to redue it all with the K2 3925 I would see about the upgraded ballscrews/nuts, servos (I don't really know if they are truly better then steppers), and I would still get 2 extra crossbraces made (gives you more places to clamp wood etc.) Of course get the upgraded Z axis. So basically, the basic machine is ok but if you upgrade most of it it will be much better

If I read Mach 3 it says my machine is going 1700 ish mm/min which would put it at 70ipm. I don't see how guys are running at 200 ipm as the ballscrews would whip around especially on the long axis and even the Z. The leadscrew on the Z axis is not supported at the bottom and I had to turn down my speed so it would not whip at top speed. I will put it to full again tonight and see what Mach 3 says the machine goes.

Hey Cbass,
Couldn't one losen the linear rail on the aluminum extursion and then put the top on and then retighten the rails. If some bend was taken out of the extursion the linear rail wouldn't be effected. That should work right?

later
taus

[cbass]

Hey Cbass,
Couldn't one losen the linear rail on the aluminum extursion and then put the top on and then retighten the rails. If some bend was taken out of the extursion the linear rail wouldn't be effected. That should work right?

later
taus

Taus,

My understanding of linear bearings is that they require precise adjustment, especially when two or more are used for the same axis. As you pointed out, loosening both rails would allow me to tighten the top to the extrusions and then retighten the rails without straining them. However, I didn't think I had the means necessary to bring both rails back into perfect alignment with themselves and everything else (especially the other axis and the ballscrew on the x). So little was true and straight that I wouldn't even know what to use as a reference. I saw loosening the rails as sacrilege, as then the integrity of the machine's movement rests on my competence to put it back properly. I paid to have the machine shipped assemble so that I wouldn't have to get into that.

Then again, lots of people on this site have made their machines from scratch. Maybe I just lack self-cofidence :violin: ....

Carlo

[sploo]

Overall I like the machine, the working size, etc. I also like the Z axis height.

Good to hear it.

I also think the rails that support the long axis (39" one) are rather small. A 1" by 3" would fit there also (1030 rail) or a 1530 rail would too. I am still thinking of doubling mine with another 1020 rail and probably will.

I take it you mean that you're planning to put another pair of 1020 alum extrusions on the insides of the current 39" rails?

If I read Mach 3 it says my machine is going 1700 ish mm/min which would put it at 70ipm. I don't see how guys are running at 200 ipm as the ballscrews would whip around especially on the long axis and even the Z.

I think both Arch and Akess have claimed 200ipm, but I don't know how they're measuring. I hope a machine with the upgraded screws will handle that, as my plan for a machine would involve making lots of circular cuts with very shallow passes (0.5mm/0.02"). I.e. I'm not going to load it heavily, but I'd need it to move pretty quickly, or it'd take forever to get through a 3/4" sheet.

However, I didn't think I had the means necessary to bring both rails back into perfect alignment with themselves and everything else (especially the other axis and the ballscrew on the x). So little was true and straight that I wouldn't even know what to use as a reference. I saw loosening the rails as sacrilege, as then the integrity of the machine's movement rests on my competence to put it back properly. I paid to have the machine shipped assemble so that I wouldn't have to get into that.

Yea, I'm with you on that one.

I'm not confident of my ability to work with metal, certainly to the tolerances required to create a decent machine, hence buying is the only option.

It seems that you got a particularly 'bad one', which is a great shame, as their machines generally look to be pretty good.

This is a big concern for me, as I'm in the UK, so sorting out problems (and getting new bits) would be very difficult, due to the 5000 or so miles, and 8 hour time difference.

It's really annoying, as I've been doing a lot of searching in both the US and Europe, and even considering shipping and taxes, I've found nothing to beat the 3925 in terms of price and performance. I wonder how insulted they'd be if I asked them to test a machine before it was shipped...

[tauscnc]

Sploo,

They should not be insulted at all (!!) as they say they test every machine before shipping. That is what makes it so dang furstrating because they can't be or they just move them a little and call it a day. If they tested mine or many of the others they should of found the SAME problems we did within mintes of having them. The person that knowns the most about their machine is the one that makes it. Why is it we all have found different issues after getting them.

After they test your ask some questions like...was there any binding in the machine? Are the rails and the crossbraces flat? Did the ballscrews deflect? What is the tolerance of the setup? Any whipping or stalling? etc. And make sure they ship it well. You might want your 3925 taken apart, like mine, to make sure it comes in good shape. It is not hard to put together at all.

taus

[sploo]

They should not be insulted at all (!!) as they say they test every machine before shipping. That is what makes it so dang furstrating because they can't be or they just move them a little and call it a day. If they tested mine or many of the others they should of found the SAME problems we did within mintes of having them. The person that knowns the most about their machine is the one that makes it. Why is it we all have found different issues after getting them.

Absolutely.

It's unfair to expect 100% of items shipped by any company to be 100% reliable, but if I could just be a bit more confident over their testing I would probably have placed a deposit by now.

I think it's highly likely I will buy one of their machines in the long run, as I've yet to find better for the price.

Ah well, I am a professional procrastinator, so it's almost certainly going to be the new year before I order. I guess the best thing to do is keep reading this forum, and learning.

[carlnpa]

To align the rails you need a reference point. The piece of 1/2" mic 6 on mine is supposed to be flat overall to less than 0.005. I measure from the rail to the plate and set at the same distance along both rails on the long axis (my x). I then can check from the top of the plate to the bottom of the short axis rail. The deviation over the entire top surface is <0.003 when aligned this way.
This is why the deflection in the long axis is such a problem when tolerance in the z axis needs to be minimized.

[tauscnc]

Hey Carlnpa,

I see. Well, I am going just leave it then. It works well for my needs and if I do decide to do anything, I might just add a top like you mentioned. That would help with any deflection and also help with a place to mount things. K2 has a .375" one if I recall and that would probably do well. I am using 3/4" MDF for now.

I had a great conversation with Ron from K2 today. Things really seem like they have changed since my first post and they seem to be working on a few different things/designs Good stuff

Lets get cutting!

Thanks again,
tauseef

[tauscnc]

Hey guys,

Long time no write Well I figured it was time to update on the orginal thread and my machine.

Overall : Very happy with it. Acutally I love it and now that I purchased VCarve Pro I REALLY LOVE IT. I don't know if I love it more because of the program or just the machine If anyone of you are looking into programs really check VCarvePro out. It makes machining way to easy!

I have K2's 305 oz/in servo motors with Gecko drives, 24 V 10 amp power. I have a 0.375" aluminum top (edited) from K2 that I finally leveled using the machine. I just cut a mount for a bosch colt trim router using the K2, came out awesome (pics coming). Mach 3.

Y and Z axis are great. X axis is still a bit gritty and the ballscrew is still bent. About 0.08 mm backlash X and maybe 0.04 mm Y and I would say 0 on the Z.

I have played with speed and the most COMFORTABLE speed I can get is around 236 in/min (6000 mm/min) jog. Pretty good. I really wanted 300 ipm but when I run a few axes it stalls. I tried a 20 amp power supply but its probably the computer. So I toned it down to about that I generally cut wood around 2500 mm/min (98 ipm) and cut my bosch mount using aluminum with a 3/4" router bit (yikes!), porter cable router, 0.5mm deep at 29 ipm. It came out great! Again will post some pics soon.

I got the bosch trim router after I could not stand the loudness of the PC router anymore.

I finally got a grease gun and put grease in my linear bearings and to my surprise my machine became quite a bit quiter.

I had to retap my mounts for the X axis as they pulled out and stripped (my many times of banging the machine to the edge ! ( I still have to put limit switches on so I fixed that part by putting in longer screws tapped into the table from the bottom.

I don't have any major plans for any updates on it...if something breaks I will update it but for now I am happy with the function of the machine... and I LOVE VCARVE PRO.

thats all

taus
www.cuttingedgecnc.com

[carlnpa]

Hey Taus, three years goes by in a hurry.
I'm still around and still using mine, it has cut Tens of thousands of parts now, though parts production has really slowed with the downturn in economy. It still is a nice part time income.
I've gone through numerous drive belts on the servos. I'm still chasing accuracy, I added one of Dumpsters' zero backlash nuts to the z axis. I still have problems getting the tool "exactly" perpendicular to the table. The motors all seem to function fine though I'm going to order spares to have on hand. Good to see you went with the 0.5" top, the 0.375" may have been too light. I am still using the original Hitachi router that I started with, the runout is still very low, but it has gotten alot louder over time and I consider it loud now, it used to be very quiet.
I think it may be time to build a new machine, slightly wider and longer, with an adjustable z that can be made perpendicular to the table. My k2 can make this new machine, except for threading the screws.

[tauscnc]

Hey carlnpa,

Good to hear from you!!! I am mistaken I do have the 0.375" top...when I talked to ron from k2, acutally he called me and told me they had one left and asked if I wanted it. They changed some of the design to allow for the 0.5" so I went from MDF to the 0.375" aluminum top. Still pretty good.

I will have to check if my router is also perpendicular to the table...from what I can tell it seems to be petty darn good. I don't chase the accuracy much as cutting foam airplanes and Vcaring wood gives me the flexabilty.

I actually am thinking of making an enclosure for the machine and putting a dust collector pipe right at the top. than I can cut away and close the machine off.

Good to hear yours is running strong, I can't say I have cut that many parts but the ones I have cut I am happy with.

later
tauseef

[tauscnc]

Hey guys, I posted my router mount here using the K2 to make it.

http://www.cnczone.com/forums/showthread.php?t=71910

Here is some other stuff I made using the K2 and Vcarve Pro

http://www.cnczone.com/forums/showth...=15995&page=11

taus

[CNCRob]

Thanks for the updates Tauseef, I was actually just looking at this thread over the weekend. I was thinking man its been nearly 3 and a half years since the last post. It seems like just yesturday.

[CNCRob]

Hey Tauseef,
I was just looking at the photos on your website and I noticed you have cable carriers on your machine now. Are they a recent addition? I don't remember you having them before. And where did you get them at? I would like to have some for my machine. Thanks- Robbie

[tauscnc]

Hey Robbie,

Yes I did finally invest in the cable guide after pinching the wire of the Z axis and blowing the fuse. The Y axis runs right through to the other side and the Z axis wire is in the cable guide.

I purchased it here: http://www.mcmaster.com/#cable-and-h...arriers/=a1byu

Mine is 1" wide and 5/8" deep, plenty of room.

Here are some pics.

Also check out what I cut last night...VCarve Pro is simply awesome!! I did not draw this but was a "clipart" and I just did the toolpath and finishing. Not much into motorcycles but man this came out great!!!

tauseef

[millmore]

Hey Robbie,

Yes I did finally invest in the cable guide after pinching the wire of the Z axis and blowing the fuse. The Y axis runs right through to the other side and the Z axis wire is in the cable guide.

I purchased it here: http://www.mcmaster.com/#cable-and-h...arriers/=a1byu

Mine is 1" wide and 5/8" deep, plenty of room.

Here are some pics.

Also check out what I cut last night...VCarve Pro is simply awesome!! I did not draw this but was a "clipart" and I just did the toolpath and finishing. Not much into motorcycles but man this came out great!!!

tauseef

Hi Carl and Tauseef,

Another year goes by...

I got my 3925 about the same time you guys did. I have to say after some teething problems and am now running parts every day and very happy with my purchase. In fact, about 1.5 years ago, I bought a new K2 3925 and both machines make carbon fiber parts everyday. It is impressive to see how quickly the guys at K2 have "grown" and expanded there business.

I have one question... I use Autocad to draw my parts in DXF and MasterCAM to write the G-code.... I have struggled getting fancy fonts (fonts skewed and compressed) into usuable G-code. Any suggestions?

Thanks,

[tauscnc]

Hey buddy,

Sorry for the late reponse. Not sure. I have used MC also and find it harder (not that I have/had any formal traning in it) but know it is more picky on line drawing, double lines, which way was it draw, etc.

I would make sure the lines are all connected, no double lines hiding under...etc.

I use vcarve pro and it checks all of that... so not much help

glad to hear the machine is running well!

tauseef