[mikemaat]

I believe the X an Y were 10mm on the ballscrew size and I want to say 3/8" or 1/2" on the motors.... Ill have to check when I get home.

I need to make a drawbar for the mill. Does anyone see any issues with using a length of B7 7/16x20" rod (7/16"-20 x 3' Plain Finish B7 Continuous Threaded Rod | Fastenal) and a 7/16" x 20 coupling nut (7/16-20 ROD COUPLING NUT, 18-8 STAINLESS STEEL | Fastenal) pinned to the top? Does it need to be any more complicated than that?

[davo727]

I have seen those couplers that have 1/4 on one end and 1/2 on the other, so you could drill the 1/4 inch end out to 10mm.

[ninefinger]

I need to make a drawbar for the mill. Does anyone see any issues with using a length of B7 7/16x20" rod (7/16"-20 x 3' Plain Finish B7 Continuous Threaded Rod | Fastenal) and a 7/16" x 20 coupling nut (7/16-20 ROD COUPLING NUT, 18-8 STAINLESS STEEL | Fastenal) pinned to the top? Does it need to be any more complicated than that?

That will be just fine, its actually one step nicer than what I'm using which has 2 nuts locktited together with the flats somewhat aligned...it survives the abuse of the butterfly impact wrench so I'm not fixing it !

Mike

[mikemaat]

Got a chance tonight to put the head onto the column with my buddies help. Actually wasn't that bad. It helps that the head has no gears in it anymore. Also my Nachi bearings showed up so I'm gonna see if I can make it out to the shop tonight and get the old races pulled.

[davo727]

1/2 to 1/4 coupler- drill small end to 10mm. $13 each

1/4 to 1/2 dia. Shaft Coupling see details for qty discounts

[nateman_doo]

1/2 to 1/4 coupler- drill small end to 10mm. $13 each

1/4 to 1/2 dia. Shaft Coupling see details for qty discounts

I have been looking everywhere for those particular couplers.

[rowbare]

Heres a pack of 4 for $38.00

Zero Backlash Flexible Coupler 3/8 to 3/8 (4 Pack) [CC-09] - US$38.00 : Homann Designs!, The preferred CNC Component Supplier

These are aluminum, good for coupling to encoders and some really lightweight machines but totally inadequate for a machine this big. Oldham couplers are the way to go for a machine this size.

bob

[nateman_doo]

For a heavy table with gibs, yes I agree. I sheared my aluminum ones on my X2. I think they will be ok with rails that don't have the extra resistance. Only time will tell for me.

[mikemaat]

Forgive my ignorance, but what's the difference between and oldham and my love joy couplers? They look to be of similiar design?

[FannBlade]

A sexy lady covered in oil is still better than an ugly lady covered in oil. :banana:

quote of the DAY!!!

Great looking build,can't believe I just now came across it. Subed for sure.

[rowbare]

Forgive my ignorance, but what's the difference between and oldham and my love joy couplers? They look to be of similiar design?

These show the differences better than I could possibly explain it:

Oldham:
[ame=http://www.youtube.com/watch?v=utEKKox2WHA]Oldham Coupling | RULAND - YouTube[/ame]

Lovejoy style:
[ame=http://www.youtube.com/watch?v=vixb5qEFx9I]Shaft Coupling ROBA-ES from mayr power transmission - YouTube[/ame]

The coupling bit between the ends on a lovejoy is somewhat compliant so there can be lost motion.

bob

[mikemaat]

So it seems the designs are similar, but the shape of the center section is different. Looks like the oldham style allows for more axial misalignment.

Do the oldham couplers have significantly less backlash than the Lovejoy style?

[AiR_GuNNeR]

So it seems the designs are similar, but the shape of the center section is different. Looks like the oldham style allows for more axial misalignment.

Do the oldham couplers have significantly less backlash than the Lovejoy style?

It depends on what the spider is made of. My X2 CNC conversion kit came with lovejoys that had a black rubber spider. I machined a new spider out of an old cutting board and it removed several thousands backlash.

[vcatalasan]

These are aluminum, good for coupling to encoders and some really lightweight machines but totally inadequate for a machine this big. Oldham couplers are the way to go for a machine this size.

bob

I totally agree! I am replacing the aluminum helical couplers that came with my Chinese leadscrews. Why because I can grab the leadscrew and twist it 5 degree. I can see the two set screws pivot. I had a lovejoy on a smaller machine that did not even do that whatsoever even with a rubber type spider.

Now I know why they also call them spring couplers.

[nateman_doo]

Probably the coolest page on couplings and other various transmission systems:
Mechanical Coupling

[Al_The_Man]

IMO if using helical couplings in servo applications, the stainless version should be used, never aluminum!
If you want close to zero back lash coupling, look at either Oldham or Disk coupling.
Actually the term Lovejoy is a misnomer to describe one type such as spider coupling, as they make all kinds, including disc.
Al.

[mikemaat]

Got a chance tonight to pull the bearing races, install the new angular contact bearings, and install the spindle cartridge. Had to use/modify a washer to space between the spindle nut and the top AC bearing as I ran out of threaded area. Gonna try and track down a proper socket bolt to replace the spindle lock handle. Ill be waiting on my last set of brackets from scott@benchtop for a week or two, so Im gonna get back to the electrical and see if I can get it all finished by the time my brackets show up. Then ill be able to spin this sucker up....

[nateman_doo]

Not a speck of dirt anywhere. You could eat off that thing. Is the head going to be gray, or is that just primer?

back to the couplers, I finally got the helical couplers and I can see why people say they are springy. I can torqe them a bit by hand. The larger set I can't but they may just work for my application with light duty. I really think I will end up spending the money on the oldhams though. I just don't like the extra wear of the discs.

[LeeWay]

I don't have any noticeable wear on my lathe after a few years. They still fit on there tightly.

I concur about eating off that machine.
It does have a clean table. I've ate off much worse.

[mikemaat]

Nope, head is painted that color. The enclosure will have a similiar scheme with the bottom and door gray and the rest white. Sort of haas-esque.