[Dan2464]

And the .001 step count video. At the end of the video you can see and hear where I hit the button to step .001 and there is no step then I hit the button to take the next step and it moves.0005. Shows me there is .0015 backlash in the system. If it stays that tight for any length of cutting time I would say that is a win. https://youtu.be/nan-X69eQJM

[Dan2464]

I have the X and Y axis back together with the aluminum gears now and all the tests show the same or slightly better than the above videos. It has turned out real well. I'll be re-cutting all of the plates now for the stepper mounts so I can CNC the pockets for the bearings and all holes will be CNC accurate. In essence now I'll be able to make the kit.
The pictures show that with the small bearing in the plate and the bronze bushing on the shaft the belt tension pulls the shaft against the outer plate. Hoping the bigger bearings will help with that since they don't have the inner race as a bronze piece. They are one piece ball bearing rather than the roller with the bronze inner race.
Also found that stainless washers are no match for the bearings that where running on them. Have replaced them with the hardened washers.

[Dan2464]

Got the mill back together and it's running great. Milling some 1/4" stainless plate about 4" x 4" for a motorcycle exhaust flange. Cutting ..025 per pass at 3 ipm. It's getting the job done. Will post some pics later of the plates. Real happy with the belt reduction. Very smooth.

[Dan2464]

So for everyone wanting to cut metal every so often with their X2... works just fine. Made these 2 flanges for an exhaust on a motorcycle. 1/4" stainless plate..

[Dan2464]

And here is a picture of the whole machine. I like the belt drive, and the McMaster Carr screws running in the Delrin seems to be working fine. Whole lot cheaper than ball screws. We'll see how they hold up in the long term.

[Dan2464]

I got asked in a PM about the acme screws. What follows is the answer.

The precision ACME screw from McMaster Carr doesn't need the ends machined. Since it is a belt reduction the hole in the gear is same size as the screw but make sure it is a tight fit. The gears are drilled through the belt tooth face so you can lock it to the acme screw with 2 long set screws 90 degrees apart. Make sure to dimple the screw where the set screw contacts the screw.
One of the build parameters was to not have to machine the ends of the acme screws. They are 5/8" so rough up one end of the threads real good for about 3 inches and use JB weld to fill in the threads then when hard use a file and smooth down to the dia of the screw. That way the washers and bearings don't get caught in the screw threads as it turns. Look at the pictures closely.

[Fastest1]

Looks good. I have always read good things about Delrin nuts. Most people report little to no wear with very little backlash.

[GreatNorthGnome]

Looks good OP. When I first did my mill I machined some acme lead screws and made delrin nuts. It was excellent, slower rapids vs ballscrews of course but zero back lash. Ran a lot of parts like that and they didn't wear down at all.

[Dan2464]

Been awhile since I have checked in with a progress report on how the standard Acme screws and Delrin nuts are working. I cut the part that was the driving factor behind building the mill and it turned out great. I also made a copy of a part that breaks at work all the time and made it on the mill also. Couldn't be happier with the performance of the screws running in Delrin nuts.
I run LinuxCNC and if there is a backlash compensation setting I don't know and haven't set it. Since there is only .0005 backlash as measured with this setup it makes great parts. The picture of the square bearing holder is 3.000 in by 3.750 in. After cutting it and using a cleanup pass it measures 3.002 in by 3.751 in. Close enough for what I need. I haven't faced the other side but the pocket for the bearing came out within .001 also. The only thing I can fault it for is a tiny bit of waviness on the walls of the bearing pocket which measure out 2.445 to 2.448. The bearing is 2.442 and it's a drop in fit which is what it is suppose to be in this application as there is a top and bottom plate that clamp the outer bearing shell. The program was told to cut it 2.442 plus .004. The peaks of the wave pattern is around .200 each instance and more on the X axis of the circle than the Y. I'll have to check the end bearings on both axis now that I have run it for awhile and snug them and recheck backlash. Could be just chatter marks as I cut that pocket with a 3/8 cutter and the X2 isn't the most rigid.
The other part came out fine and I'm going to cut a few out of Delrin.

Also a picture of a 5/8 single bit fly cutter/mill bit. Worked pretty good.

Fusion 360 makes all of this possible. Love that program since Cam is built in.