Colchester bed repair

[Dave123]

Have a Colchester Master with alot of wear in the ways just before the headstock, .020” in one section. This is enough to make it difficult to use when alternating between different lengths of materials without making adjustments to correct.
One idea to improve things is to have the bed ground, this will help remove the error from the bed way. I realize that most likely a major part of the wear is going to be is in the bottom of the saddle, as this area is not hardened.
I understand that the wear to the underside of the saddle can be compensated by applying Rolan, or Turcite then scape these areas to fit. It sounds like Applying Turcite to the bottom of the tailstock is not the best option, better to machine and scrape these areas then shim to adjust for elevation.
My question is how do you arrive at the elevation the saddle needs to be to maintain the correct contact for the carriage drive gear. It is obvious that on my machine the contact between the gears is not correct now.
Hopefully there is a better method other than trial and error.
I am not particularly looking to return the machine to its out of the factory tolerances, more wanting to make it a useable machine once again.

 

[52 Ford]

Have a Colchester Master with alot of wear in the ways just before the headstock, .020” in one section. This is enough to make it difficult to use when alternating between different lengths of materials without making adjustments to correct.
One idea to improve things is to have the bed ground, this will help remove the error from the bed way. I realize that most likely a major part of the wear is going to be is in the bottom of the saddle, as this area is not hardened.
I understand that the wear to the underside of the saddle can be compensated by applying Rolan, or Turcite then scape these areas to fit. It sounds like Applying Turcite to the bottom of the tailstock is not the best option, better to machine and scrape these areas then shim to adjust for elevation.
My question is how do you arrive at the elevation the saddle needs to be to maintain the correct contact for the carriage drive gear. It is obvious that on my machine the contact between the gears is not correct now.
Hopefully there is a better method other than trial and error.
I am not particularly looking to return the machine to its out of the factory tolerances, more wanting to make it a useable machine once again.

If you're going to have the bed ground, I wonder if it would help to have it built up with flame spray welding. That way when it's ground, you don't have that extra 20 thou to compensate for in the carriage.

 

[john.k]

take it to an experienced lathe bed grinder.....they will do it right,and tell you how much to build up the saddle.....and expect to pay a fair bit for the job.

 

[4GSR]

When I reground the bed on my Lodge & Shipley I had, I made some aluminum pieces that mounted on the ends of the saddle wings in place of the wipers with adjusting screws that allowed me to raise the saddle. By adjusting these end pieces, I was able to raise the saddle to as close as I could get it in alignment with the leadscrew and feed rod. Last, I aligned it square to the headstock spindle so it would cut square when facing off on a work piece. After that was done, I was able to run different thicknesses of stacked up feeler gages to come up how much shim I would need. If your going to install Rulon, I suggest that you remachine the saddle ways, too. If not, you are going to have lots of scraping to do to get things aligned properly. I applied Moglice to my saddle and eliminated the need to do any scraping other than scraping the middle out as it is usually required in scraping and fitting. Somewhere is the thread I started on doing the Moglice application. Search for 20" Gap Bed Lodge & Shipley Lathe for more information. Ken

 

[Demon69]

Have a Colchester Master with alot of wear in the ways just before the headstock, .020” in one section. This is enough to make it difficult to use when alternating between different lengths of materials without making adjustments to correct.
One idea to improve things is to have the bed ground, this will help remove the error from the bed way. I realize that most likely a major part of the wear is going to be is in the bottom of the saddle, as this area is not hardened.
I understand that the wear to the underside of the saddle can be compensated by applying Rolan, or Turcite then scape these areas to fit. It sounds like Applying Turcite to the bottom of the tailstock is not the best option, better to machine and scrape these areas then shim to adjust for elevation.
My question is how do you arrive at the elevation the saddle needs to be to maintain the correct contact for the carriage drive gear. It is obvious that on my machine the contact between the gears is not correct now.
Hopefully there is a better method other than trial and error.
I am not particularly looking to return the machine to its out of the factory tolerances, more wanting to make it a useable machine once again.

There are usually keepers underneath the saddle (apron side), these dont really wear per say so you can measure the present clearance to the bottom face of the bed for a good idea. You can also measure bed to lead screw/drive shaft with he saddle parked in the worn area, compare this reading to the ends of the bed, tailstock end will likely be near unworn.
GL

 

[Dave123]

There are usually keepers underneath the saddle (apron side), these dont really wear per say so you can measure the present clearance to the bottom face of the bed for a good idea. You can also measure bed to lead screw/drive shaft with he saddle parked in the worn area, compare this reading to the ends of the bed, tailstock end will likely be near unworn.
GL

Thanks for the information / tips guys, exactly the kind of response I was looking for, rather than "take it to a dealer and expect to pay "

 

[Dave123]

All great advice, thanks again

Dave

 

[Dave123]

Thanks GL
What are the keepers you are referring to ?

Dave

 

[Demon69]

Thanks GL
What are the keepers you are referring to ?

Dave

The keepers on mine were just L shaped efforts bolted to the saddle hooking around the bed. Guessing they would have been fitted pretty close originally.

If you have any might be able to see them tucked in behind the apron, if you can get a feeler in there it should give you a ballpark figure of saddle+bed wear.

Main thing to concern yourself with is that the rack meshes and the drive shafts and screws don't bind through X/Y, iirc the tolerance is pretty generous.

 

[Peter from Holland]

3 other approaches
Make a oversize gear
Grind off the apron
If the gear below the drive gear is offset (to the left mostly) and has plain bearings
Turn 2 excentric bearings so you can swing that gear in position
Done that on a weiler once Worked like a charme
I am no fan of turcite or moglice here Originaly it is CI on hardened CI If you just grind both bedways and carriage and then scrape in the carriage to fit it is all original again
Deal with the lowered position
Plenty of good options
I know Richard does not like this way of doing
But Ruemema does it this way

Peter

 

[Demon69]

I dropped the box-shafts-rack on my DSG when I did it, if the design of the machine allows why not, keeps the plastic out of it.