[cowanrg]

I am working through the conversion of my PM30 and needed to do something with the Y axis to keep chips off the ballscrew. I looked all around for pre-made bellows but they are pretty hard to find and usually absurdly expensive. However, Tormach sells replacements for their mills and their prices (on the bellows) are quite reasonable. They are here on their website (under replacement parts).

Interesting fact, they sell them for the front and the back. I ordered one of each. When I got them they were marked with the different part numbers, but there's no discernible difference between front and back. However, the front ones are $10 more. So just get 2 of the rear ones, and save some money.

They take a bit of modification, but it can all be done with some tin snips and a Dremel. I just used some scissors (before I wised up and grabbed the tin snips):

Attachment 245752

The front and the back are pretty much the same in terms of what you need to modify. They are made to sit up a bit higher, and for wider dovetails. I wanted mine to sit much lower since I needed it to clear my oiler fitting. I just cut the plastic down so they sat closer to the base. I drilled two holes in the front (and back) of the saddle to mount them, and made a plate for the front to mount:

Attachment 245754

This also has the added benefit of covering the coupler for the Y as well. This was my first real part made on the mill, so it was pretty exciting. The rear just attaches into the column, no plates needed. Here's what it looks like from the front:

Attachment 245756

And from the side, showing the front and back bellows. They do a great job of catching chips, there's no real way to get chips onto the ways, other than lifting the bellows up and shoving chips under them. They come down about 0.25" to 0.5" below the ways.

Attachment 245758

All in all, the Tormach bellows ended up costing less than $50 and took just a few hours to modify and install.

[cowanrg]

BTW, I need to do some updating to my blog, but if anyone is looking to do a conversion on a PM30 (or any of the several variants), I have pretty much the entire mill modeled in Solidworks. I'm going to release it to 3D Content Central for download once it's a bit more complete, but if anyone wants a zip of the files, let me know.

[cadguy247]

BTW, I need to do some updating to my blog, but if anyone is looking to do a conversion on a PM30 (or any of the several variants), I have pretty much the entire mill modeled in Solidworks. I'm going to release it to 3D Content Central for download once it's a bit more complete, but if anyone wants a zip of the files, let me know.

I'd love to have a copy of the files if you don't mind

[cowanrg]

Cool, I think I'll just host it on my site, I'll reply back later today with a zip once I get it uploaded.

I'm redoing the X, Y, and Z bearing blocks with all the proper shims and part numbers and such.

[cowanrg]

Here's the assembly.

[cadguy247]

Thanks for the files, they are a big help.

I sent you a PM

Thanks
Kyle

[Wiggles84]

can you post dimensions on the bellows open and closed?

looks more than wide enough for a G0704

Thanks,
Andrew

[cowanrg]

They are 11" wide (more like 11 1/16") and roughly 2" tall. They compress down to 1" (if you really compress them good), and 1.5" if you are just pushing them without much force. They expand to around 12" (total length) if you just pull them apart, and about 13 if you give it a tug. So yeah, they are pretty perfect for a mill of this size. I have the front one mounted on the motor mount which extends about 2.5 inches past the end of the saddle, and even at full extension, it's fine. (factor in about 1" for the bellows themselves, then 8.5" worth of travel, and 2.5" back from the saddle, that's 12", so it has a tiny bit of slack still).

They might be a bit big on the G0704, but they would certainly work. Bigger shouldn't hurt anything.

[Wiggles84]

I have about 9.25" travel on my G0704 Y axis hard stop to hard stop. I do not plan to use it "to the extreme", but its nice to know it could reach

Word to your mother,
Andrew

(sorry about the Vanilla Ice in there. Started to type to the extreme and couldn't help myself! )

[cowanrg]

How are you getting 9.25" worth of travel? I could get about a half an inch more in back, but the table would go underneath the Z dovetails, and if I go too much further up front, it would hang too far over the edge.

[Wiggles84]

I machined the base per the holy Hoss plans for extended travel. Also using the column spacer, head spacer and extended Y front mount






Andrew

[cowanrg]

ah OK. yeah, that's a LOT of extra material on there. I think the bellows should work just fine for you then. In the back, I scrunch them up to 1" to get the full travel out of the mill. They compress down to 1" just fine, as long as you use a button-head screw on both mounting points.

You may have a bit of a hard time getting it to fit underneath your oil fittings up front. I had to do all my trimming for that. If I didn't have the oil fittings, I wouldn't have needed to trim anything, just trill a couple of holes.

I could get the thickness down to 1" for the span of the saddle. If the distance from the bottom of your fitting to the base of the mill is less than 1", you might have a hard time.

[Wiggles84]

thinking the back might get bellows. I've been looking at just mounting a cover plate to the front of the saddle.

time will tell,
Andrew