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Taper Pins Size in Colchester Triumph piece gap

CZACC

Plastic
Joined
Nov 26, 2016
Hi,

I'm trying to reinstall the piece gap in a Colchester Triumph 2000. According to the measures I took the size of these taper pins (2) should be #10, but now I'm unsure about it. The pin enters but they got stucked at the middle , may be is because the hole diameter was dirty or deformed by the lack of care in the past.
I order to avoid any problem, I would like to know if some of your know the right size of these taper pins, in the user manual this informations doesn't appear.
Thanks a lot
 
Since no one else answered I have a question for you. Why put it back? The reason I ask is that I've never pulled a gap piece out, I was always afraid it wouldn't go back in as perfectly as it started. That was based on things I'd read over the years, but recently my brother sent me this; http://mail.centurylink.net/service...emoval.jpg?auth=co&loc=en_US&id=160590&part=2

Granted this is Shop Fox but he mentioned that he'd read something like that before. The main suggestion was similar to "If you do take it out do not reinstall it". Wow huh?
 
I doubt lathe manufacturers are that silly to add an expensive feature that is then impossible to use.

Cheap lathes you might have issues. I am not sure if Colchesters are considered cheap or not. They were certainly in their day the cheaper ones, but compared to the cheap of today they would be classed maybe medium quality.

The gap should be scraped to fit at the factory.
 
The interesting thing is that I searched PM about it, as I too remembered reading somewhere strong recommendations to never remove the gap. Since I've never pulled a gap I have no idea that is based on personal knowledge, only what I've read.
IIRC what I had read was that after pulling a removeable gap it is almost impossible to get them back to the accuracy they originally held, which may be true. Then it becomes a question of how much degradation of the original accuracy does one accept?
It may be that any degradation of accuracy is so minor that it is generally ignored, but that leaves the warnings out there, why are they out there? Old wives tales?
I also assumed that a gap should be replaceable but I've never needed one out bad enough to risk it as I have larger lathes than the replaceable gap lathes can accommodate.
 
I finally found some threads about it;http://www.practicalmachinist.com/vb/general/gap-bed-engine-lathes-removing-gap-146261/

Should the taper pin be a standard taper? 1/4" per foot isn't it? Weare working over a lathe now that has a bunch of short taper pins that are tapped, so just get some that just fit all the way into the hole and start cutting off 1/4" at a time until they start to get tight, then drill/tap the big end for later extraction. That's what I plan to do on mine.
 
From another forum on both good and bad experiences pulling the gap;

This is fact: A gap may or MAY NOT go back in place perfectly,no matter how clean and careful you are with it. We had a Grizzly 16" lathe in the toolmaker's shop. I had to remove the gap to true up a 20" bandsaw wheel that had been welded. The gap would not quite go back perfectly,no matter what I did. The gap stuck up from the rest of the ways so that the carriage was deflected upwards some after replacing it. And,the gap was file hard. Fortunately,we soon got budget to get a better,larger lathe soon after that. The only cure would have been to try milling some off the bottom of the gap piece. But getting it parallel and just right would have been a tricky job. It would have had to be indicated all over to determine where,and how much metal would need to be milled off,and if it had to be milled at a small fraction of an angle. Then,it'd have to have been gotten into the mill just right. At worst,the whole bottom could have had about .015" milled off parallel,and shims put in under the gap piece as needed to take care of any taper. Careful use of an indicator could have gotten the ways of the gap back parallel. That would have worked,but would be sloppy machining.

I have the same model lathe at home(bought the 2 together in 1986). I had a 24" swing job to do. Reluctantly,I removed the gap. Luckily,it went back into place perfectly flush with the rest of the ways.

Apparently some stress can be relieved when these gaps are removed,letting them warp a small amount. So,good luck. Both these lathes were made in Taiwan,mind you. I couldn't swear to the castings being properly aged. They all do it in ovens these days,though.

It is not a good thing to leave the gap out. Unless you have a lathe with an English type carriage(big carriage wheel on the right end instead of the left end),the gear runs off the rack before you can get all the way to the chuck. And,even worse for face plate work. You'd be 5 or 6 or more inches away at best. Closer with a chuck,but still not all the way to it AT ALL. I didn't measure it,but noticed it when I had the gap out of the 16" lathe at work. The English Myford lathes have no gap piece at all,but their carriage arrangement allows for the lathe to work any way. Their gaps are not very wide.


Even if you could reach the chuck with a cutting tool,etc.,it is still not a good idea to have much of the carriage hanging out in mid air.

I wrote this in a very offhand way,but you get the idea. And these are real experiences. Oh,yes,the temperature in the shop was constant. And I am a maniac for getting such things CLEAN. I was so happy that my own lathe fitted back perfectly!!!:)

So, Based on all I've read after using google for a search engine today there is no way I'll ever pull a gap piece out, nor pay extra for a lathe with one.
 
i woul imagine it makes a difference how the machine is supported/twisted.
 








 
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