Milling Machine Table Repairs

I need to repair some drill holes in the table of my Tom Senior milling machine.

I am thinking fill the holes with weld and then re-grind the whole surface.

I would appreciate any ideas as to which welding process to use (MIG, TIG or stick) and which filler to use.

Any ideas?

Stephen,

Why not snatch victory from disaster and thread them instead for additional clamping variations?

Regards Brian

So have you got the surface grinder to re-grind the top surface & maybe the underside to eliminate any possible distortion? Welding does seem a bit drastic for cosmetic purposes.

Tony

I filled some holes in my day on b/port tables if holes are not to big i reamed and turn up a peg from good quality cast iron and drive in with a hammer an finally stone to a almost invisible finish

Hi Stephen,

I've used locktite epoxy putty for similar jobs. Once set hard it just files down. Once set it is very hard to see it, the colour is so close to cast iron.

Don't touch it with a welder! Somewhere on this forum you will find the late great JS mending a mill table with a tee slot broken out by milling a pocket, bolting in a new bit and re-milling the slot.

You can plug the holes with another piece of cast iron. Just drill a hole flat bottom, to cover the damage and with a dremmel or air grinder make groove about halfway down the bore to make a slight key. Turn a plug slightly longer than the hole depth and a tight fit but not press fit. File a slight flat on the plug to allow air to escape when you hammer in the plug. Just hammer in and give it a good hammer and peen the top. You can then file and Finnish with a stone and you can't find where it was. Unless it is halfway across a T slot it is easy but evan with a bit of finess you can get away with that as well. You can overlap these repairs to do a chain of damage.

David

Welding would risk warping and or cracking the bed. If you can clean up the holes, it would be much safer to glue, or screw in plugs which can be carefully brought down level. D G's method is excellent, as long as the holes are not near an edge. You can get a Devcon metal repair putty in cast iron which would match the colour.

Edited By old mart on 06/07/2020 21:33:26

Are these drill holes very adjacent to the T-slots? May need a different approach than some of the suggestions above, if this is the case. Welding is still not a sensible option.

There is only one option for welding in a repair like you suggest and that is to have it laser welded. Absolutely zero distortion and better weld strength than parent metal. Problem is finding someone to do it! I have used laser welding but the best people to do it are at RN Dockyard in Portsmouth - there the problem is accessing the place as you need to know someone who will vouch for your 'security level' is good enough for what is basically a military premises (although it is a private company).

The other benefit with laser welding is that dissimilar metals can be fused - like titanium and steel. The 'cold' action of the weld was demonstrated to me by the manager who put his finger right next to a weld run and asked me to do the same - I did with some trepidation but was shocked by the absolute lack of any heat within a 1/4" of the weld seam.

Welding seems a poor idea ... for all the reasons mentioned above. Inserting a plug or threaded rod with loctite and milling it flush seems a better idea. If you absolutely must melt metal, you might have more luck with silver solder or brazing, perhaps?

Unless you have access to some pretty sophisticated heat treatment equipment steer a wide berth from welding cast iron. Heating to fusion temperatures caused rock hard/extremely brittle carbides to form at the periphery of the weld. If you really must repair it using molten metal use nothing hotter than braze.

Some pictures would help.

The bed of the Tom Senior at the museum had milling scars left by some ideot, and I milled the surface down about 1.5mm, and it took months of rubbing on the surface table to get it true again. About 90% of the marks were removed.

Edited By old mart on 07/07/2020 16:26:03

Gentlemen

Many thanks for all your suggestions - I take it's a thumbs down for the welding solution

The biggest hole is almost half over a T slot so the plug method may not be suitable.

However, I like the laser welding idea and am on the case - I will update you with pictures if I am successful.

Steve

Stephen,

If you want to go down the laser welding route PM me and I'll forward the contact details of the RN dockyard people. A typical price for a Vintage cylinder block weld is about £150

You can try these ABR Specialist Welding Ltd
2 Haines St, West Bromwich B70 7DS
0121 525 1319
They can weld anything, laser specialist as well as other types as well.

David