[kuroguy]

So I got the bearings for the y and z axis as free samples from PBC bearing. The target size is 18"x36"x4". I've started work on the y and z axis. This machine will be made from as many materials that i can scrounge. I'm using some 1/2" acrylic, 3/4" oak plywood, and whatever else i can beg borrow, or steal. Here's pictures of the free bearings and the beginnings of the y and z axis.

[kuroguy]

Made a little more progress. Continued working on the z axis. Bearings for the lead screw will be here tomorrow. I'll locate them and then make the mount for the stepper as well as the support for the bottom of the lead screwwhich is 1/2"-10, 5 start.

[kuroguy]

Anybody got any opinions on whether i should support the z lead screw from both ends or if support from the top end only is sufficient? Itis 1/2" and only about 9" long. If I support from the top end only, I'm thinking stepper coupler - thrust bearing - radial bearing housing - thrust bearing - shaft collar.

[CarveOne]

Available DIY plan sets show it both ways. If no bearing is at the bottom end of the lead screw there won't be any lead nut binding that would result from imperfect alignment of a lower bearing relative to the top bearing. When you don't have machinery to drill or bore holes for the bearings accurately, you have to be creative when making upper and lower bearing mount plates that align perfectly. My first machine was built from Solsylva plans that had no lower bearing. The two machines I built afterwards both have bearings at each end of the Z axis lead screws. Backlash due to side loads on the cutter is usually limited by the bearings on the guide rails and is usually not transferred to the lead screw. Only the up and down backlash due to plunges would need the thrust bearing and collars to keep it from damaging the router or spindle.

I put thrust bearings above and below the bearing mounts with a collar on each side to insure that no thrust loads get to the router in either direction. I've seen machines that work fine with no thrust bearings at all.

[kuroguy]

I think i'll do one end for the z and both ends for x and y. Of course, i reserve the right to change my mind. As an aside, i'm really enjoying designing and building this thing.

[kuroguy]

The radial bearings I ordered arrived today. I got 10 for $8.80 shipped off of ebay.

Attachment 186682

Also made some more progress tonight. Here's the z axis ready for the stepper and lead screw. I'll scrounge some 7/16" rod to make the standoffs for the stepper and order some couplers and thrust bearings next week.

Attachment 186684

[kuroguy]

Started work on the gantry. Stepper just sitting there. It'll get some rods between it and the top of the car.

[kuroguy]

Made 3 stepper mounting brackets tonight using the drill press and a jig to drill the screw holes in some delrin rod i purchased on ebay to make collars and shaft couplers, $10 for a 1" diameter x 12" long rod; enough to make 3 couplers and 6 collars. This weekend, with some luck, I'll be making shaft collars and couplers and curring ,drilling, and tapping some aluminum rod for the stepper motor mounts.

Attachment 186996Attachment 186998

[kuroguy]

Got the delrin rod and started machining it. First i cut a 2" piece of 1" delrin rod and chucked it up on the lathe. Used a jacobs chuck in the tailstock and first went all the way through with a 1/4" drill, then 1-1/4" in with a 1/2" drill bit. From there it was over to the drill press. I clamped the delrin rod in the wood jig i made and cut 4 notches in it for clamping screws (4-40 x 1/2") with a 1/4" forstner bit. Next was the clearance hole for the4-40 tap and then i loosened up the top hole so the screws wouldn't bite on the top half. A quick run through the 4-40 tap and then i slit it on the table saw. I must say, this stuff machines like; well, plastic. If you've got a drill press and a lathe (optional) there's no need to spend $18/coupler when you can make them from $2 worth of delrin.

Next I chucked up the aluminum rod in the lathe and drilled holes in them for an 8-32 tap. $4 worth of aluminum rod and i've got all of the stepper mounts. Here the lathe is required, but I fabbed them on a wood lathe.

Here's how the delrin fits in the jig for drilling. Once clamped, off center drilling is a snap.



And here's the z axis with the stepper and lead screw mounted. I'm making progress.

[kuroguy]

Here's the Z axis on the Y axis.

[kuroguy]

Alright, it's design input time. Your insight is greatly appreciated. You can see from the last photo that the y axis is 3/4" oak veneer plywood and the y rails are a c section (I could not get them to flex at all). Will this be stiff enough for cutting aluminum? Should I shore it up by making the y axis a torsion box? Should I take a wait and see attitude since adding the torsion box therewould be a piece of cake?

Now for the side panels for the gantry. Is 3/4" ply going to be stiff enough foraluminum cutting? I figure this is the weakest link in the table.I could easily make these torsion boxes too but I also want to keep the gantry weight as low as possible.

Your input is greatly appreciated.

[kuroguy]

Spent about an hour making shaft couplers and collars. I started by cutting 2" of 1" delrin on the chop saw

Attachment 187438

Then to the wood lathe and drill all the way through with a 1/4" drill

Attachment 187440

Then 1" deep with the 1/2" drill bit. I mark the depth with some masking tape on the bit.

Attachment 187442

Next I take 1/16" off the end so it clears the outer collar of the bearing.

Attachment 187444

Then to the table saw for a slit lengthwise.

Attachment 187446Attachment 187448

Then to the drill press for the forstner bit to make a notch, then 2 more drilling steps before tapping with 4-40. The aluminum flat prevents the coupler from rolling during drilling.

Attachment 187452Attachment 187454Attachment 187450

And the finished product.

[kuroguy]

Eight pieces of 3/8" rod drilled and tapped to 8-32 completes the X and Y stepper mounts.

Attachment 187644

As an aside, do people typically comment here or do they tend to just look?

[LeeWay]

I just had a chance to read this. Nice work so far, especially on the couplings. Nice score on the samples too. You may be able to engrave aluminum, but not sure about cutting it. It may be possible for some type of high speed machining depending on the spindle choice.
I would say that a torsion box might be your best bet to make it as rigid as possible with those materials. It can't hurt.
Keep up the good stuff documenting with pictures. Nice thread so far and I'm interested in seeing the finished product and how well it works.

[met4life]

I am wondering how long it took to get those samples from PBC and also how did you manage to get the redi rails? Their samples say you only get a 4 inch piece of rail.

How are you liking the uniglide for the Z axis? Do you see any issues about backlash or any flaw in the way the carriage mounts onto the rail?

[kuroguy]

I purchased the redi rail on ebay, 36" for $87. The redi rail cars came from 2 smple requests, one that I made about a year ago and one that another coworker made independently. when I saw he had it, I asked if he needed it. He didn't, and gave it to me. Regarding the Uniglide, the specs are rock solid. There does seem to be a slight bit of runout in it, but I assume it is the same for all rail/solid bearings. It is solid with just enough screw holes to easily fit the bill. I'd certainly use it again for the z axis. The nice part is that it is really 2 rails in one piece built 3" apart from eachother and a 4" long pair of bearings in one solid car. This design automatically aligns the left rail to the right rail since it comes as one piece.

regarding the redi-rail, i cannot feel or measure any runout at all in this system.

samples took about 3 weeks to arrive as I recall.

[met4life]

I picked up a 10" Drylin rail/carriage on ebay about a month ago and installed it on my Z axis. There was a little bit of play in how tight the carriage rides the rail but it glides really smooth and my parts look perfect, no signs of backlash/movement during cutting. I placed an order for some samples about a week ago, I really wanna compare the Uniglide to the Drylin. On PBC's site, I honestly didn't notice the big ad on the left side that said "Free Samples" when I was determining which rail to get, that could have saved me some money!

Nice machine so far, I really like your couplings. Keep up the good progress! I'm gonna watch this thread cause I'd really like to see your finished machine and see some first cuts!

[kuroguy]

i'm selling some old sailing crap on ebay which should finance the remainder of this project. in the mean time, I'll be working on the X axis rails (cutting and drilling), building the carrier for the router, and finishing up the design for the gantry. I asked the structural engineer at work for some pointers on stiffening the gantry in hopes of being able to machine aluminum and he gave me some good pointers. i'll begin cutting wood this week and will post more pictures as I progress. I figure I should be done with this build in 2-3 weeks.

[kuroguy]

Today I ordered the last of the parts for my table: antibacklash nuts and linear carriages for the X axis. It won't be long now.

[kuroguy]

Worked on attaching the Zaxis car to the Z leadscrew tonight. It was somewhat of a pain in the ass. Also tapped the y axis car and attachedthe low profile antibacklash nut to it. You can't see it, but it is there. Next I'll work on the router bracketsand then the gantry.