View Full Version : Damaged screw keep

02-21-2005, 04:46 AM
I'm in the middle of restoring a Colchester Master mk1. lathe. During disassembly of the cross-slide I came across this, http://img.photobucket.com/albums/v676/meleschko/cross-slidescrewkeep.jpg
Now, I have some ideas of how to fix this, but I can't make up my mind (not the first time). If you gents have a few moments to spare I would really appreciate your suggestions here... thanks


02-21-2005, 06:34 AM

Due to the rust, I doubt you'd be able to put the pieces back together successfully.

Would it be possible to completely turn away that flange and make a new flange to slide on and perhaps silver solder in place?

Ted Coffey
02-21-2005, 06:35 AM
[This message has been edited by Ted Coffey (edited 02-21-2005).]

02-21-2005, 06:54 AM
<font face="Verdana, Arial" size="2">Originally posted by SGW:

Due to the rust, I doubt you'd be able to put the pieces back together successfully.
Thanks for your answer SGW -
Well, there isn't any real rust here, the picture just came out that way (the piece is pretty dirty though).
The broken off piece fits perfectly. I considered silver soldering it myself, but then a friend of mine, who normally gives sound engineering advice suggested cutting a grove along the breaking line and welding it... but I'm thinking it might be a bit drastic on a delicate piece like this… am I being a chicken here?

Alan in Oz
02-21-2005, 07:12 AM
Is there a hole through the broken piece to the shaft area or am I just seeing crud there, has it been pinned before. I would tend to go along with SGW suggestion as I think too much heat would not be good, also a lot of oil into the metal, making a good joint harder.

02-21-2005, 07:13 AM
What is the material? It looks like a casting. If that is the case, grooving and brazing or building it up with braze and machining might be a better approach then welding.

02-21-2005, 08:15 AM
If you don't want to put enough heat on the piece to weld or braze, I would disassemble the assembly and clean it. Soak it in a good solvent to get all of the dirt, grease, etc. off of it and then gently heat it to drive off anything in the pours of the metal. Since the pieces fit together, used JB Weld or some other epoxy to attach the broken section. Wont be as strong as a weld or braze repair but will probably work in this application. I would use a larger washer under the attaching bolt if there is room when you reassemble.

Hope this helps.


John Stevenson
02-21-2005, 08:31 AM
Not the first one I have seen like this.
Clean it up, glue it back in place to act as a packer/spacer and make a U shaped piece that slost up from the bottom with two holes to match in the top of the U legs.

SWG's way is also a nice way and more pleasing. You could even use two allen grub screws at 90 degrees if you don't fancy the heat approach plus a liberal dob of Loctite.

From the pic it also looks like you could turn the flange off and some of the diameter behind the dial and make a top hatted piece, Stronger, more pleasing and new clean material.

Many ways to do this it's more personal choice and available equipment .

John S.

[This message has been edited by John Stevenson (edited 02-21-2005).]

02-21-2005, 09:49 AM
It doesn't look like there's any great amount of side force on the flange.

I'd clamp the broken piece in place and drill through the broken piece and into the shaft.
A sloppy hole for the pin is what you want.

Choose a pin that you can rough up with file or grinder.
You don't need too much, just a few notches to help lock everything together.

Then, clean everything with a non-petroleum solvent - lacquer thinner, acetone etc.

Mix up some JB Weld, get it into the oversized pin hole and along the break area.

Clamp the break area then slide the slathered with JB pin into place.

I've repaired a few things like this and the pin adds a lock to the holding together bit.

If the JB failed and I doubt it will, then you could revert to machining a new piece or whatever is required.

02-21-2005, 10:08 AM
It looks like cast iron, perhaps malleable cast iron, which is even better. If thoroughly cleaned & degreased, it would take only a tiny TIG tack weld (1/8"D) on each end to resecure. Heat input would be minimal, distortion shouldn't be a problem.

02-21-2005, 11:45 AM
Bevel the crack and braze with Harris Welco 17FC.

02-21-2005, 01:48 PM
Thank you all gentlemen,
Well I asked for it. Instead of 3 different approaches I now have 8-9 and my head is spinning... No seriously, I'll give each of your suggestions a good thought before I go destroying the piece beyond repair.. ahem, I mean before I restore the piece to a point where no one could ever tell it's been broken.
Thanks again I really appreciate it.