[Drill] Drill Press Rack & Pinion Fix?

[old toolmaker]

I have an old 1956 Toro drill press that I am rebuilding. I am almost finished but I am not happy with the back lash between the rack on the spindle and the pinion gear on the hand lever shaft. There is too much slop in the vertical direction, allowing the spindle housing freedom to move up and down about .025"-.030". This affects drilling in a bad way, allowing the drill to hog rather than a smooth drilling action. The spindle really can't be allowed much up and down movement.
Does anyone have a good solution to tighten up the fit? I have thought of an eccentric bushing to be able adjust the fit as one possible fix. Any other ideas?

Dick

 

[Chipper5783]

Have you check for wear of the bearing areas on the pinion (either in the housing or of the actual pinion shaft)? The actual gear mesh is probably not really worn (very low speed operation).

I had a similar issue with the apron hand wheel on my little lathe. I ended up disassembling the apron, making a new bushing to support the pinion and replacing the shaft of the pinion (which took some thinking as the shaft and pinion were one piece - now they are 2 piece). It all worked very well, significantly improving the backlash in the apron hand wheel. http://www.hobby-machinist.com/threads/smart-and-brown-1024-lathe-another-trip-to-the-auction.30870/

Perhaps you could share some pictures to make things clearer?

 

[old toolmaker]

Thanks for the response. The rack and pinion seems to be in very good shape as you suggested it would be. There is some small amount of clearance between shaft and hole on the handle end. The left hand end of the shaft is a very sloppy fit. This could be the main issue. I will disassemble today and and take good measurements of both ends and report back.
Dick

 

[Chipper5783]

You are right that play is probably the main issue. Moving that pinion just a small amount further out (i.e. wear in the bushing) will make a significant difference in the clearance of the pinion to the rack.

 

[oldbob]

I bought a Chinese drill from Hare and Forbes, was told it was cheap and cheerful, the rack and pinion have 2+mm backlash that when a drill breakes through the chuck drops causing the drill bit to jam on occasions. I guess the fix would involve boring the head holes oversize and installing eccentric bushes enabling backlash adjustment. Then there is the spline on the quill, about 3-4° radial play. All good for agricultural jobs. Hafco did send me a replacement quill assembly BUT it was the same, the machine body is the issue. I did buy a small vatiable speed drill which is great up to 6mm, I guess these were made for drilling PCBs, this is good but I dont remember my then 25 year old Waldown having all these spindle issues. Maybe there is a better brand?

 

[Downunder Bob]

I bought a Chinese drill from Hare and Forbes, was told it was cheap and cheerful, the rack and pinion have 2+mm backlash that when a drill breakes through the chuck drops causing the drill bit to jam on occasions. I guess the fix would involve boring the head holes oversize and installing eccentric bushes enabling backlash adjustment. Then there is the spline on the quill, about 3-4° radial play. All good for agricultural jobs. Hafco did send me a replacement quill assembly BUT it was the same, the machine body is the issue. I did buy a small vatiable speed drill which is great up to 6mm, I guess these were made for drilling PCBs, this is good but I dont remember my then 25 year old Waldown having all these spindle issues. Maybe there is a better brand?

G'day, most of the chinese junk that H&F sell is exactly that, junk. Your idea of eccentric bushes is a good one and will work a treat. The big question is the rest of the machine worth that effort. Might be better to just get a decent machine. H7F do have some Taiwanese machines that are mostly ok. Although I prefer Modern machines in Melbourne. Good luck.