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View Full Version : Replacing that sloppy table screw in OLD machines



Bill Pace
10-07-2009, 10:22 PM
We seem to have acquired quite a few new members with 'newbie' status and since I still consider myself a 'newbie' also, I thought this repair might interest them.

I recently brought home a 1941 G&L surface grinder, that was showing its age in a few areas (while other areas were in very good condition?) One of the badly worn pieces was the table cross feed screw & nut, 1" diameter, about 2 feet long with 5tpi acme thread. This is a typical screw/nut that similar would be found in lathe lead screw/cross feed, mill table feed screws, etc, and in the older lathes/mills is typically worn like this one. So if you come across an old tool that has sloppy action in the screws, even tho there may not be replacement screws available, they can be made -- relatively easily.

This is the old worn one on top, with the new screw and nut on the bottom, we used a piece of 1" stressproof for the new screw. Lane demonstrated the art of cutting the acme threads for me - instructions and commentary included:D Man! gotta love that guy!!
http://i22.photobucket.com/albums/b301/pace1980/IMG_1546.jpg

Here is a close up of amount of wear on the screw, probably during its life of service it preformed the same function on a daily basis, causing the concentration of wear in that relatively short area.
http://i22.photobucket.com/albums/b301/pace1980/IMG_1547-1.jpg

tattoomike68
10-07-2009, 10:36 PM
Nice , Looks like Lane kicks butt.

Doozer
10-07-2009, 11:07 PM
Where I used to work, they had a Galemayer and Lewis surface grinder that was a bigger one, a model 35 or 350 I think. I believe the chuck was 8 x 22" or something. I really liked the one tenth downfeed. That thing would repeat really well. And when you cranked down 2 tenths, you got it. The ratcheting powerfeed was really sloppy though. Like shifting a 41 Chevy truck. Anyhow, I really like that machine. Funny, I notice Norton built a grinder that looked almost exactly the same. My friend has a Doall that also looks mighty similar, and interestingly it has a tag that says something about being made by Taft Pierce. Your screw looks great!

--Doozer

Alguy
10-08-2009, 12:54 AM
How was the nut cut? single point (insert or ground) or a tap?

Walter
10-08-2009, 01:42 AM
I just finished doing a new rod and nut for our Induma Mill. The original screw was worn as badly as yours and the nut eventually gave out completely. While there was no problem at all making the screw we had no material on hand or time to wait as the mill was badly needed, so I ended up cutting out the old nut, making a couple of lands and lock holes, then poured Babbitt in with the new screw centered in the old nut case. It worked surprisingly well. While this isn't the way I'd have preferred to do the repair, it did get us back up and running not only the same day, but cheaply. I also chose to go with 1144 for the new screw.

Bill Pace
10-08-2009, 09:46 AM
The ratcheting powerfeed was really sloppy though. Like shifting a 41 Chevy truck. Anyhow, I really like that machine.

Yeah, that design is pretty rough (this one is a model 25, 6x18)-- wouldnt even work when I got it, this was another place that Lane came to the rescue, we took the assembly out (that was fun!) and made a new shaft & a couple other items and at least it functions now, although still in the 41 truck mode:( Still, since the whole concept of a powered table was thunk up by G&L only a couple yrs earlier in '39 and a war was going on, its some pretty neat engineering!


How was the nut cut?

Single point -- he nut could have been a problem, thats quite a hunk of brass, and a piece that big is not something I - or any of us - would usually have in the scrap bin, but I had spotted that hunk at the scrap yard some time back and didnt hesitate to grab it, think I paid 15-20$

kf2qd
10-08-2009, 10:42 AM
Hunt up a piece of cast bronze (somebody here should have a clue about a supplier) and turn one. Make sure to check as to whether it is a left hand or right hand thread.(made oone wrong one time...) If it had a soft nut before, there is probably less wear on the screw than the eye thinks it is seeing. Left hand nuts are easier to make than right hand - you chase them coming out of the bore rather than going in.

Doozer
10-08-2009, 11:12 AM
I like how the hydraulic cylinder that drives the ratchet for the cross feed acts like an accumulator to cushion the table reversal.
I rember the one at work had a gate on the shifter to help in finding neutral, but any slop in the linkage makes the gate hurt rather than help you. I think it was a model 35.

--Doozer