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Missing dowel pin hole on Clausing 4900 lathe.

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  • DR
    replied
    Originally posted by JoeLee View Post
    How much is removing the dowel pins going to allow the headstock to move in case of a crash ?? a few thou ??? That's not going to save anything.

    JL...............
    I don't recall the exact amount of movement, maybe 1/16"? Apparently lathe builders don't agree with you.

    Leave a comment:


  • JoeLee
    replied
    Originally posted by DR View Post
    Some precision tools, in my case a CNC lathe, use dowel pins to align the head stock to the bed. Once aligned and bolted down the dowel pins must be removed. This allows the headstock to move in case of a crash.

    Sometimes rebuilders don't remove the dowel pins. Then when there's a crash the pin holes can be elongated which means the factory headstock alignment is lost forever.

    It may be possible the Clausing lathe builders felt one pin was enough to establish a pivot point for alignment.


    That's possible but the diagram calls for 2 pins. But, things are subject to change without notice.

    JL................

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  • JoeLee
    replied
    Originally posted by DR View Post
    Some precision tools, in my case a CNC lathe, use dowel pins to align the head stock to the bed. Once aligned and bolted down the dowel pins must be removed. This allows the headstock to move in case of a crash.

    Sometimes rebuilders don't remove the dowel pins. Then when there's a crash the pin holes can be elongated which means the factory headstock alignment is lost forever.

    It may be possible the Clausing lathe builders felt one pin was enough to establish a pivot point for alignment.
    How much is removing the dowel pins going to allow the headstock to move in case of a crash ?? a few thou ??? That's not going to save anything.

    JL...............

    Leave a comment:


  • DR
    replied
    Some precision tools, in my case a CNC lathe, use dowel pins to align the head stock to the bed. Once aligned and bolted down the dowel pins must be removed. This allows the headstock to move in case of a crash.

    Sometimes rebuilders don't remove the dowel pins. Then when there's a crash the pin holes can be elongated which means the factory headstock alignment is lost forever.

    It may be possible the Clausing lathe builders felt one pin was enough to establish a pivot point for alignment.

    Leave a comment:


  • larry_g
    replied
    So this thing has worked for some 50 years and now you think it has a defect? I would not worry about it now.

    lg
    no neat sig line

    Leave a comment:


  • JoeLee
    replied
    One dowel pin will get you pretty close as far a up and down and dead on left to right. All you have to worry about is the left side either sitting low or being raised too high.
    Your bolts are going to limit that. Before you tighten the 2 SHCS down just make sure that you have proper gear tooth engagement between the QC gear box and the quadrant arm fits properly.

    Now that you have me thinking........ Looking at the breakdown of my 5900 series it only shows the one pin on the right. I don't remember if there were two when I restored my machine. But the diagram does say 2 required,

    JL......................

    Click image for larger version  Name:	aabc-22-3.jpg Views:	0 Size:	152.8 KB ID:	1947973

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  • Doozer
    replied
    If your potential plan is to bore the missing hole.
    may I ask what is your plan to ascertain the proper alignment
    for the gearbox in order to locate said hole ?
    Whatever that plan happens to be... Can you employ your method
    and then simply tighten the bolts, and potentially forgo the drilling
    and pinning ? How did it function before? Was there a problem ?

    -Doozer

    Leave a comment:


  • Dan_the_Chemist
    replied
    Originally posted by elf View Post
    Usually there are left over parts when putting something back together. This is the first time I've heard of someone losing a hole🤨
    Decades ago I worked in a lab that used some pricey equipment. Every 6 months one of us would have to do the PM on a gizmo that cost something like 2x our annual salary. It wasn't that bad if you worked methodically, and didn't drop the sapphire pistons or misplace the gold o-rings... Yeah, that kind of thing. So one day Ken was the guy who drew the short straw. He spent the morning with the manual open going through the PM procedure step by step... As he took the thing apart he put the parts in beakers (chemists, yanno) and put them on the bench. Then he went to lunch.

    We went down to the machine shop and got some spare parts out of the spare parts drawer. A couple of 4-40 machine screws, a 4-40 nut, and a weird shaped bit of stamped metal about 1" by 1/2" by 1/4" that looked like it should hold something... complete with two holes that would fit the machine screws. We salted those into the beakers and waited.

    Ken came back from lunch and started the reassembly procedure... carefully cleaning, lubing, torquing, etc... He was almost finished around 3 PM when he began to fret about having parts left over. We all watched surreptitiously as he paged through the maint manual, looked at all the diagrams, and spent 30 minutes trying to identify the location of the part. Then he finally said a curse word and picked up a tool with the intention of disassembling the instrument looking for the proper location. We stopped him and explained what we had done.

    He did not take it gracefully.

    Leave a comment:


  • JoeLee
    replied
    Originally posted by elf View Post
    Usually there are left over parts when putting something back together. This is the first time I've heard of someone losing a hole🤨
    Good one !!! Maybe it grew back in.

    To answer the OP question, after all these years I would just leave it. Just make sure nothing binds up when you put it back together. It may only need a pin on one side and was left that way purposely.
    I'll have to check my 5900, it's basically the same thing. I had a 4900 at one time.
    You're more likely to do more harm by trying to drill a hole than if you just leave it.

    JL.......

    Leave a comment:


  • elf
    replied
    Usually there are left over parts when putting something back together. This is the first time I've heard of someone losing a hole🤨

    Leave a comment:


  • Rock
    started a topic Missing dowel pin hole on Clausing 4900 lathe.

    Missing dowel pin hole on Clausing 4900 lathe.

    I was gifted a Clausing 4900 lathe that had been taken apart for transport. I cleaned it up, repainted, replaced some bearings,etc .I am now putting it back together and found that the left hand dowel pin locator hole in the quick change gear box was not bored at the factory. You can see a mark where it should be caused by the gear box pressing the pin into the bed as it was bolted down. Has anyone else noticed this on a 4900? Should I try to bore the hole , a real pain, or just put it together as is?
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