Fixing a cross-feed nut

[DiscoDan]

I have a Burke No.4 x-y table and the y-axis brass/bronze nut is very worn out. It is unlike most of the brass/bronze nuts I have seen. I was thinking of just repairing it since the only one I can find is on ebay for $100 and the condition is really unknown. McMaster Carr sell brass/bronze nuts with Acme threads and they have one with the thread I need that is round. I was thinking of boring out the worn-out nut and press fitting in the replacement from McMaster Carr after I turn down the diameter. Does that sound like a reasonable fix? The MMC website says that bearing bronze is more wear resistant than brass so that's what I was going to use.

Thoughts or suggestions? Pic of Burke nut attached.

 

[pontiac428]

I think you could bore it out and install an Acme insert, you'd just need to pin, thread, or swage the insert into place so that it can transfer the full load without any movement.

Your other choice is to make your own replacement. Last, there is an Acme nut guy on ebay that does popular lathes... he may be able to do a Burke for you. I have his business card at home if you are interested. I think his name is Hawk.

 

[benmychree]

I repaired a table nut in an old (1906) Brown & Sharpe mill that I had years ago, by boring out the old nut and making a new sleeve for it of #660 bearing bronze and silver soldering it in place; pressing in a replacement in may cause undersizing of the insert, resulting in too tight a fit, Loctite is also an option, combined with drilling and tapping a hole lengthwise with the insert right on the interface of the casting and sleeve, then loctiting in a section of screw to prevent slippage of the sleeve.

 

[hman]

You can also make a cheap and very close-fitting leadscrew nut out of Delrin or similar plastics. I've seen several how-to-do-its on the web over the years. Here are two I just found with a quick Google:

DIY Anti Backlash Nuts - Super Cheap and Simple

DIY Anti Backlash Nuts - Super Cheap and Simple: This nut can be used for any kind of linear motion. Weather it is on a 3D-Printer, a CNC or a camera slider. It only takes an hour to make and works amazingly well! Delrin is the perfect material to slide over metal. There is very little wear and it…

www.instructables.com

Making Acetal leadscrew nuts... DIY - Denford Software & Machines

One added technique I've seen previously, which I didn't see in either of these, was to coat the leadscrew with soot (from a yellow flame) before melting the Delrin onto it. The soot acts as a mold release.

 

[markba633csi]

I would probably buy the nut and then make a new steel block, with the plan being to epoxy the nut into the block. Maybe a pin or two also for strength.
M

 

[DiscoDan]

I would probably buy the nut and then make a new steel block, with the plan being to epoxy the nut into the block. Maybe a pin or two also for strength.
M

That's not a half bad idea. I may try fixing it first and if I fail and "F" it up I could do this. Or just do it for fun I guess.

 

[markba633csi]

Half bad? I think it's only about 6.42 % bad

 

[weewill]

Contact The D. C. Morrison Co. 859 581 7511 www.dcmorrison.com They sell parts for the burke mills. I have bought the bevel gears for the knee on a burke no 4. They are good to deal with.