Rack and Pinion on Drill Repair

[mi3gto]

Folks, I am after a bit of advice please. I have just got hold of a Meddings floor standing drill (cheap). One of the old models. It is in good condition overall except for one missing tooth on the rack of the spindle and what I can see is two broken teeth on the pinion.

I want to repair this before putting it into service. What is the best way to repair the missing, broken teeth. Build up with weld and re grind after removing the parts? Cut a insert? How what? A new part is not available from Meddings so repair is the only way. If welding and grinding what type weld? TIG? What rod?

There are also a few small holes in the table around the drill clearance hole, the table is cast iron. What is the best way to tackle these? I have access to a full tool shop if required but would like to do as much myself as possible. George

 

[penfold]

What pitch/mod is the rack and pinion? It may make more sense to obtain a replacement rack and pinion; there are cheap ones on ebay. For a pillar drill table really whatever you can get to stick to the material; some racks/pinions aren't made of great material. If it's cast iron it may be you need to make a tooth and braze it in place.

 

[gordon stephenson]

You could even drill and tap where the teeth are missing and fit a row of suitable size allen bolts and dress to suit the profile.

 

[mi3gto]

I may have misguided you. It's not the rack and pinion that raises and lowers the table, it is the drill spindle itself and the pinion that lowers the spindle. The spindle is one piece so cant replace just the gear teeth. The teeth are cut into the spindle. I may be able to machine out the original teeth and insert a standard stock rack?

The pinion gear may be easier to get hold of but none on eBay, do you know of any on eBay or suppliers of stock gears and racks??

Looking like drilling and pinning/brazing the lost tooth on the spindle. As for the pinion gear if I can find a similar pitch tooth count diameter width stock gear I could bore it out to make a gear ring and then after turning down the original pinion fit the new gear ring silver soldering or brazing it to the core? Or just drill and braze as per the spindle.

I have been hunting around the web looking at gear repairs, I am gussing that this will involve the same process?

Would the strength of the repair be as good as the original tooth?

As to the table repair, I will try a few rods etc to see what will stick?

What pitch/mod is the rack and pinion? It may make more sense to obtain a replacement rack and pinion; there are cheap ones on ebay. For a pillar drill table really whatever you can get to stick to the material; some racks/pinions aren't made of great material. If it's cast iron it may be you need to make a tooth and braze it in place.

 

[mi3gto]

Gordon any links to photos that show this being done? I was thinking of drilling for pegs and brazing them in place, never thought of taping and threading them in. Are you suggesting screwing them in to the head is flush with the shaft and shaping the head? what do you call suitable size? that is the socket of the allen bolt will present a hole if the head is to big and I have to file into it. Badly explained but you get my drift.

You could even drill and tap where the teeth are missing and fit a row of suitable size allen bolts and dress to suit the profile.

 

[Robotstar5]

Gordon any links to photos that show this being done? I was thinking of drilling for pegs and brazing them in place, never thought of taping and threading them in. Are you suggesting screwing them in to the head is flush with the shaft and shaping the head? what do you call suitable size? that is the socket of the allen bolt will present a hole if the head is to big and I have to file into it. Badly explained but you get my drift.

If you think the hex head voids would be a problem, use bolts (not set bolts) and screw in 'til the plain shank "bottoms out" then cut the head off and grind/file the shank to size?

 

[gordon stephenson]

As per Robotstar5. choose a suitable diameter allen bolts.bottom them out in the tapped holes using high strength locktite,then cut off the heads and shape to match other teeth.
Do one peg at a time so that you can cut off the head and have the next peg touching the one before.Ie: no gaps between pegs,

 

[Flathead_Dave]

It's worth getting a catalogue from here,just for the info.

http://www.davall.co.uk/davall-stock-gears/davall-stock-catalogue/

Meddings say they can supply parts for 90% of their machines,but prob not cheap.If yours is a MF5 MK2,then it's one of the other 10%.
S/H parts are scarce,machinery dealers keep them to patch up old machines because of the price they fetch.

I'd be carefull welding the table,with cast rods you stand a chance of cracking it if you get it wrong.
I used to use some universal arc rods called Stubs 65.They were good on clutch pressure plate lugs without heating,but very hard to grind down.
I'd drill and tap the holes,and screw some studding in flush,and sand it down.

 

[mi3gto]

Thanks for the info. Instead of Locktight would it not be better to have a loose thread and then braze (what rod/flux?) them in place filling the void between the pegs/bolts with braze?

Has anyone any comments or tried this type of rod?

http://www.muggyweld.com/?view=rod7x

smoke and mirrors? UK equivalent?

I don't know what model of drill it is, I will get photos today and see if you guys can ID it. Thanks so far with all the help.

George

 

[gordon stephenson]

I would not braze, heating for brazing will soften the bolts. I'm assuming this repair is only on a hand feed system and not mechanised,

 

[penfold]

HPC gears is the one which springs to mind, but there are others. A less risky way of filling holes in the table is metal loaded epoxy; it's not as hard as cast iron but in practise you probably won't notice any difference.

 

[mi3gto]

here is the drill.....

http://photobucket.com/meddings

anyone have a manual/parts list/drawings?

 

[mi3gto]

I am guessing this is a M4 Pacera?