Reply with QuoteHi LongRat - have you got any further yet?
I meant to ask, are all of those linear rails for your router, or are you planning to put some on the mill?
Cheers.
I recently received a set of bearings from VXB I bought for the BP quill drive I'm building. I bought a pair of 7202s, a 6202 and a 5202. I'm quite impressed with the quality of all of them. The 7202s (single-row A/C, $14.95 for the pair), when clamped up tight have what feels like the perfect pre-load - a very slight drag, and zero backlash. The 5202 (double-row A/C, $9.95) also has zero lash, and is perfectly smooth. For dirt-cheap bearings, the quality seems remarkably good.Originally Posted by LongRat
Regards,
Ray L.
Hi LongRat - have you got any further yet?
I meant to ask, are all of those linear rails for your router, or are you planning to put some on the mill?
Cheers.
I'm putting an auxiliary z axis on the mill, to hold my high speed spindle. That will use a couple of the linear rails. The rest of them are for the router.
I have made some progress, I just finished the nut mount for the z axis. This took a while on the X2 - the 25mm ballnut is huge. Here is a picture before I bolt it up to the nut.
The next stage is to modify the stock cast iron end plates to hold my new bearing blocks.
That's a very nice looking part
Might it not be easier to just make completely new bearing mounts from some flat stock? Do you have a lathe handy, or do you have to do everything on your X2?
Thanks.
I have a 9x20 lathe and an Emco Unimat 3. Definitely easier to reuse the existing parts I think, as I intend to have the new angular contact bearing blocks 'floating' on the existing end plates so that the exact alignment can be adjusted in, then I will lock the two parts together with allen bolts. Cutting completely new bearing blocks would be a lot of work, I could bore them on the lathe but to get a nice profile would still take a mill, and the X2 is a bit too small for that task. It may still come to that (maybe for X), but I'm pretty sure my plan will work for Z and Y.
Before I forget, here is the drawing I supplied when sourcing the ballscrews. Note that there's no need for such a long length on the Z screw, I just ordered a screw that would fit in the whole column length.
Top is Z, middle is Y, bottom is X.
I mounted the nut mount to the head, in the end it was such a close push fit that I didn't see the need to bolt it in, although I can always do this at a later date. So I have my Z nut and screw installed, only have to finish the bearing block and motor mount now. Before I can do the motor mount, I really need to get a decent coupler. The ones I got from Linearmotionbearings are not going to cut it, they are only 19mm OD aluminium helicals. I want to get some Oldham couplers, these are what I used on the X2 and I really like them. But they are SO expensive! Anyone know any good sources that aren't too pricey? I'm looking for the 33mm OD ones ideally. RS sell them but you are looking at £10-£12 per hub, and then you have to buy the sliding disc. To complete the mill I'd be looking at something close £100 just for 3 couplers!
I think I did actually get mine from RS, but they weren't quite that expensive two years ago.
Have you tried Marchant Dice - they're a bit cheaper: http://www.worldofcnc.com/products.asp?recnumber=56
But really, can't you just make some on your X2 from 25-30mm aluminium rod? You could then just buy the torque-discs from RS...
I'm pretty sure I've seen some very nice all-in one slotted couplers made by someone on here in the Tormach forum... - I think this is it: http://www.cnczone.com/forums/showpo...31&postcount=1
Make your own couplings - they'll cost next to nothing. I made these for my X2 eons ago out of scrap. They are zero backlash, took about an hour to make several of them.
Regards,
Ray L.
Yeah I guess I'll have to make them. Really was hoping to avoid that if possible, my lathe's out of action with a busted belt and I have a lot on at the moment that is taking my time. Plus, my bandsaw is also broken, the motor went up in flames when the blade jammed. Guess there's nothing for it though.
Wow, you've really fallen out with the good-luck-fairy!
Given what you've just posted, I'd be tempted to just buy some so you can get back to at least one working machine ASAP. Whenever I'm wincing at a price, I try and rationalise it by comparing it to the cost of a tank of petrol, or a really good hangover. Most things seem quite reasonable after that
Good Luck!
Yeah, that's good reasoning. I still have a couple of machines working though, small lathe and X2 CNC still operational!
I've decided to go half way and buy the plastic discs as suggested, and I'll make the alloy hubs. Ordered a belt for the lathe on ebay, so it should be here pretty soon - although it is coming from the US.
If you have the room, it pays to make the diameter as large as possible, to eliminate backlash. You want the hubs to be a snug sliding fit in the slots in the plastic - they should not move really freely. In case the construction is not clear, these are slightly different from Lovejoys. The plastic piece has a 1/4" slot running across each face, with the two slots 90 degrees to each other. I just slotted it with a 1/4" endmill, then milled the hubs to get the proper snug fit. All the parts were rough-cut, then I assembled the three pieces with a shaft through the middle, and put them in the lathe and turned the outside to make it all pretty.
Good luck!
Regards,
Ray L.
Zapp Automation have couplers for £13.50 ex.vat. (I have no connection to them, other than ordering a few bits from them).
http://www.slidesandballscrews.com/3...ing-p-186.html
Thanks for the tips. I'm familiar with the construction of Oldhams, I made one for my 4th axis conversion for the X2.
Ben, good link, thanks. However that's not the true Oldham design that I'm looking for unfortunately - very nice price though. I prefer the Oldham design as there's something not so nice about relying on the compression of the plastic in my mind. Plus, Oldhams can tolerate a LOT of misalignment, not that I am going to have much I hope...
How's about you buy the cheapie ones, and then post a video of the new machine cutting better ones
Longrat have you had a look at Farnell? http://uk.farnell.com/oldham-couplings
Yes I have, ended up ordering some torque discs from there for 1/3 the price, once you factor in VAT and postage.
I'll be making the hubs as soon as my lathe belts arrive. I've got the rest of the Z axis done now so should have a working axis fairly soon!
Hi Long Rat - what motors and drivers are you going to be using, and what sort of rapid speeds are you aiming for?
I'll build it up with NEMA 34 steppers, 450oz.in running on 39VDC @ 6A. This is the overkill set up currently on my X2.
I would like to see the same rapids I run on the X2 if possible, 1700mm/min on X and Y. On Z I currently get 1500mm/min, I don't expect to achieve that with the WMD30. If performance ends up being poor, I will upgrade my power supply voltage, and then maybe also put on some larger NEMA 34 motors. I'm using Gecko G201s so I have a lot more head room there, should it be necessary.
