Rack pinion shaft for Clausing Colchester series 8000 lathe

Helder22 · Aug 23, 2011

Hello guys,
I just purchased
a Clausing Colchester 13x40 lathe (8000) series and its mostly in great
condition. Even the ways are ok.
Heres a pic:

However the pinion that rides on the rack under the main ways in completely worn
out. There are no more flats on the teeth, just sharp points. I called Clausing
and they want $1250.00 for a new pinion, so that's not gonna happen. OUCH!

It occurred to me that I could make my own pinion for a lot less or maybe I
could get an off the shelf pinion and press/heat fit it to a shaft I could
easily make myself. Does anyone know what the specs are for this pinion? Its
part number 72838-0 on the manual. I called Clausing and they would not give me
or did not know the specs by the way

Helder

ken moss · Aug 23, 2011

Get the boston or martin catolog out count the teeth check the od and go hunting it helps to have a set of gear pitch gauges I will check the pitch on the rack of my 13" today sometime Ken

rklopp · Aug 23, 2011

There's a guy in Houston area, Frank I think, who sells Colchester parts cheaper than OE. His user name is something like FDKIII. Maybe he'll chime in. Google "Colchester parts site:practicalmachinist.com".

ken moss · Aug 23, 2011

then there is this Clausing Colchester lathe 13 inch apron | eBay

Helder22 · Aug 23, 2011

Thanks guys, Id seen that apron on ebay already but theres no way to tell if the pinion is any better than mine.
Ive also already spoken to Frank. Im actually going to be getting a couple of parts from him but he doesnt have a pinion right now and would have to have one made. Replacing the worn gear with one from Boston is what Im pending towards. I figure I could turn the worn gears out of the old part, bore out the new gear, shrink fitting them together.

AlfaGTA · Aug 23, 2011

The rack on my 15" Colchester is a:
20* 10 pitch
Don't know if that is what the 13 inch machine uses.....
Easy to check if you have a set of gear gauges. Can get them from your local bearing house..(Bearing Engineering perhaps)

Once you know the pitch and pressure angle easy to buy a redi-made replacement from Boston Gear etc.....just need the number of teeth on the old pinion and you can then graft the new pinion to the existing apron shaft.
Fit with key and light press and hold all together with a screw or bolt, replacement in the future then becomes easy.....
Cheers Ross

AlfaGTA · Aug 23, 2011

Of course you realize that one reason that the pinion becomes worn is that the carriage might be worn and have dropped and that makes the tips of the pinion do all the work. (poor engagement by having too great an installed distance)

Check the height of the feed rod and lead screw (with half nuts engaged) ans the carriage at mid bed....the screw should be flat with the ways ...same height at the ends of the bed as it is at the right side of the carriage.

Cheers Ross

Helder22 · Aug 23, 2011

I actually hadn't thought of that, and I hope it's not the case. I'll take a look at it.

Mark McGrath · Aug 23, 2011

As these lathes are renowned for having soft,noisy headstocks and beds (yes,I know it says they`re hardened) I would be wary of the condition of the rest of it when the saddle pinion is so badly worn.I have seen and heard a lot of very noisy,rough Colchesters but not seen one so bad the saddle pinion was worn away.
Don`t ever judge a Colchester by the condition of the paintwork.If they had put the same quality into the engineering that they did the paint they would have built a truly great lathe.

Helder22 · Aug 24, 2011

The rest of the lathe seems ok to me. Needs a couple things but overall its ok. I was taking a closer look at the gear and im feeling a little more comfortable about its condition now. The outer diameter of the pinion is still the same as it was when new. I can tell because one end of the pinion is not riding on the rack and is not worn, so I can compare the condition. Actually the flats on this end and are not that wide at all to begin with. Must be the design of the gear I guess. The ones at the college have much larger flats. I looked last night.

heres the best picture I could take:

heres another that looks like mine:

http://images.hellotrade.com/data/L/P/MY-1224364/rack-pinion_250x250.jpg

the ones at the college look more like this one:

http://1.imimg.com/data/6/M/MY-1110512/Pinion-Gears_250x250.jpg

quasi · Aug 24, 2011

another thing that can wear the pinion out is operating the carriage on the x axis with its lock on. Machinists do this sometimes because the carriage wears and gets a little play vertically . The properfix is disasembeling the carriage and surface grinding the plates that engage on the bottom of the front way.

I just replaced the pinion on a Harrison lathe by turning the old one off and pressing- pinning setscrewing a replacement on from Boston gear. It was 10 DP as I recall.

petryss · Oct 19, 2020

https://www.ebay.co.uk/i/264012363663

Dan from Oakland · Oct 19, 2020

Are you certain that the pinion teeth are badly worn? I'm about 97.5% certain that your 10 tooth pinion is cut on an enlarged blank due to the low number of teeth. Even a 20 degree PA 10 tooth gear would be badly undercut if cut on a standard size blank. Enlarged pinions often times have teeth that appear to be more pointed than a standard gear. It is standard practice for pinions to be cut with a shifted profile and are sometimes referred to as "long addendum". I realize this is an old thread, but possibly this info will help someone down the line.

Tyrone Shoelaces · Oct 20, 2020

The original post is 9 years old guys.

Regards Tyrone.

john.k · Oct 20, 2020

I ve though about fixing stuff longer than that.....hell, three generations of cats now have preferred the water drip from the cistern in the loo to their own water dishes.

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Rack pinion shaft for Clausing Colchester series 8000 lathe

Helder22

Plastic

ken moss

Stainless

rklopp

Diamond

ken moss

Stainless

Helder22

Plastic

AlfaGTA

Diamond

AlfaGTA

Diamond

Helder22

Plastic

Mark McGrath

Diamond

Helder22

Plastic

quasi

Stainless

petryss

Plastic

Dan from Oakland

Titanium

Tyrone Shoelaces

Diamond

john.k

Diamond

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