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Suggestions sought; how to remove the rack on my Atlas 618 lathe

Woodsman 22

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#1
I am trying to restore an Atlas 618 lathe that was given to me. I have it all apart to clean, replace parts that need replacing and then paint and put it back together again. However, I am stuck at trying to get the rack off the lathe bed. The screws came out easy enough, but there are two taper pins there to locate the rack and hold it in place. One of those pins seem to be accessible from the inside , but the other was installed where the bed is thick- right at one of the webs.There are threaded holes for the screws all the way through the bed, and also one hole where it seems I could try to punch out one of the taper pins from the inside of the bed, but no way to get at the other from the inside.
These pins are in there TIGHT! I am afraid of trying to pry up the rack from the outside of the bed because I would probably screw something up in a really big way. I would really be interested in hearing from anyone with any suggestions on how to get this off without damaging the rack, the taper pins or the lathe bed. Thanks in advance for any help.
 

Ulma Doctor

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#2
are they taper pins or split roll pins?
rarely are taper pins used in places with blind holes.
even manufacturers realize that things need to be taken apart and replaced.
in my day job, i play doctor (read :Hack ;) ) on packaging and processing equipment from a lot of different manufacturers.
i usually see taper pins used for sprocket, cam, and gear retention on shafts where there is provision for removal.
usually, with a large hammer and a swing from behind the ear, (maybe a few expletives for good luck:eagerness:)

in assumption that they are true taper pins:
in your situation, i would remove the pin you can get to and get out.
then see if the rack can be upset from its present position by pushing down on the rack
you may get lucky and the rack will rotate , holding the pin in the movement. a few up and down cycles will remove a taper pin.
a putty knife, then a small wedge or small screwdriver inserted between the bed and rack can help to gently separate the rack from the bed

secondary advise, if there is a taper pin head sticking above the rack you could try to grab it with a pair of vise grips and extract it.
the taper pin may become damaged, but if you have no other way to remove it- there is a way!
(you can always consider modifying for use with spring pins for ease of assembly/disassembly)

maybe someone else has tackled this job on that lathe that may be able to add further instruction

it was put on in a factory, i'm sure you have the capacity to take it off :)
 

TakeDeadAim

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#3
Taper pins are often used in machine tool assembly to hold pieces in place, location pins if you will. On older machines I have seen them put in blind. During the rebuilding process I was able to remove them by drilling and tapping them for a screw then using a screw, washer and piece of tubing or socket the pin can be pulled out by pulling the pin as the screw is advanced against the washer on top of the tube or socket. Best way I know of to remove blind pins.
 

Woodsman 22

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#4
are they taper pins or split roll pins?
rarely are taper pins used in places with blind holes.
even manufacturers realize that things need to be taken apart and replaced.
in my day job, i play doctor (read :Hack ;) ) on packaging and processing equipment from a lot of different manufacturers.
i usually see taper pins used for sprocket, cam, and gear retention on shafts where there is provision for removal.
usually, with a large hammer and a swing from behind the ear, (maybe a few expletives for good luck:eagerness:)

in assumption that they are true taper pins:
in your situation, i would remove the pin you can get to and get out.
then see if the rack can be upset from its present position by pushing down on the rack
you may get lucky and the rack will rotate , holding the pin in the movement. a few up and down cycles will remove a taper pin.
a putty knife, then a small wedge or small screwdriver inserted between the bed and rack can help to gently separate the rack from the bed

secondary advise, if there is a taper pin head sticking above the rack you could try to grab it with a pair of vise grips and extract it.
the taper pin may become damaged, but if you have no other way to remove it- there is a way!
(you can always consider modifying for use with spring pins for ease of assembly/disassembly)

maybe someone else has tackled this job on that lathe that may be able to add further instruction

it was put on in a factory, i'm sure you have the capacity to take it off :)
"are they taper pins or split roll pins?
rarely are taper pins used in places with blind holes"

- Thanks for your input! As it turns out, another someone else mentioned that he has the same lathe and it has 1/8" straight pins (not spring type "roll" pins), so that is probably the type of pins that are in mine too, I just couldn't tell from looking at them in their 'installed' position.

Trying to work them loose as you describe isn't going to work because the rack is tight up against the bottom of the front lathe ways. I will try taking the accessible one out and then try prying the other end off with a putty knife as you suggested. That might work.
 

Woodsman 22

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#5
Taper pins are often used in machine tool assembly to hold pieces in place, location pins if you will. On older machines I have seen them put in blind. During the rebuilding process I was able to remove them by drilling and tapping them for a screw then using a screw, washer and piece of tubing or socket the pin can be pulled out by pulling the pin as the screw is advanced against the washer on top of the tube or socket. Best way I know of to remove blind pins.
Thanks, and yours is a good suggestion, but these pins are small- only 1/8 inch in diameter. Plus the end that is accessible is rounded as well as set slightly below flush with the rack itself. Would be really hard to drill and tap something that small, I think.
 

Bob Korves

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#6
It is pretty easy to bend a rack or otherwise damage it while taking it off the lathe. If it is in bad shape and needs to be replaced, then do it. If you are doing it as part of a cleanup or restoration, and it appears to be in decent condition, you might consider just leaving it alone and undamaged. It is not that difficult to clean it up well enough in place and then tape it off and paint around it.
 

Z2V

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#7
I m with Bob on this. I just taped mine and painted around it.
 

Woodsman 22

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#9
It is pretty easy to bend a rack or otherwise damage it while taking it off the lathe. If it is in bad shape and needs to be replaced, then do it. If you are doing it as part of a cleanup or restoration, and it appears to be in decent condition, you might consider just leaving it alone and undamaged. It is not that difficult to clean it up well enough in place and then tape it off and paint around it.
Not in bad shape at all, but I think your point is a wise one. I didn't know they could be bent easily, so I think I will follow your advise about leaving it in place. That said, it is very greasy and dirty with a lot of accumulated old encrusted chips and grease around it. It does badly need a cleaning. I was going to take the lathe bed to a nearby car wash and use their wand to pressure degrease , soap up and rinse off the whole lathe bed (after taping up the ways to protect it). I just hope the water getting under the rack doesn't cause it to rust. Thanks for your input.
 

Wreck™Wreck

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#10
Drill and tap through the rack in several places, remove a length of thread from a screw of the same size and jack the rack off of the pins, this is a common practice with tight fitting machine components and is sometimes done by the manufacturer, taperlock drive bushings and scroll chucks for example.

As seen below, the non threaded holes pull the taper into the part and hold it tight, to disassemble remove the screws and place them in the threaded holes and jack the taper apart.
The only reason that the OEM would no do so is cost.

And no, this will not effect the gears use, it is merely a method of disassembly.
http://controlscentral.com/product_pictures/Large/H1.jpg
 
Last edited:

4gsr

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#12
I've drilled and & tapped threaded holes in gear racks that we installed on machines just for that reason, to allow you to remove with ease. Generally the tapped holes were adjacent to the dowel pin holes next to the bolt holes that held the rack on the bed. These were big sections of rack like 4 or 6 DP.
 

Woodsman 22

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#13
Drill and tap through the rack in several places, remove a length of thread from a screw of the same size and jack the rack off of the pins, this is a common practice with tight fitting machine components and is sometimes done by the manufacturer, taperlock drive bushings and scroll chucks for example.

As seen below, the non threaded holes pull the taper into the part and hold it tight, to disassemble remove the screws and place them in the threaded holes and jack the taper apart.
The only reason that the OEM would no do so is cost.

And no, this will not effect the gears use, it is merely a method of disassembly.
http://controlscentral.com/product_pictures/Large/H1.jpg
- That is brilliant! I was vacillating back and forth over this; "do it, don't do it". Your method does provide a way to get that rack off without bending it. Thanks!
 

Woodsman 22

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#14
I've drilled and & tapped threaded holes in gear racks that we installed on machines just for that reason
"Wreck" said the same thing and a big thank you to both you guys. I would never have thought of that. So if I do decide to take that rack off rather than just clean and paint around it, if it gives me any grief I know there is a way to get it off the bed for sure. This idea is going into my bag of tricks.
 
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