How to True up the table/box?

tertiaryjim said:
Madmodifier
To me the geometry of the shaper is still a bit of a mystery.
The ram can pull down into the cut or be pushed up depending on tool geometry and material.
Thats a consideration for any operation you'll do on that machine.
I spent some time searching through Machine Tool Reconditioning and came up with a oil clearance of 0.0005" to 0.00125" for the ram
ways. This would be for a machine with properly scraped surfaces for oil retention, not a well worn machine, and since I couldn't find
any reference to shapers I determined the clearance from other machines with sliding ways listed in the book.
Perhaps Richard could confirm or correct this figure.
It's easy to check your clearance with a feeler gauge inserted into the ways front and back of the machine and with the ram in at least
three positions. If you cant slip a 0.0015" gauge in there it's really good.
The vertical column ways of my machine, as best I could measure, leaned back 0.0007"/ft.
This would give rise to the outside of the table but when checking the carriage I found variations of as much as 0.004" that was due to
original scraping and not wear. this would prevent perfect adjustment of the gibs and could allow the table to sag and move under pressure.
Further, the vice wasn't true and it's surfaces weren't flat.
I guess what I'm trying to say is that the machine may not have come from the factory correctly produced and with wear and time you will
have to live with some problems or rebuild it.
If you're not going to rebuild it then check the vice for problems that you can correct and cut the table true with a load attached.
One thing you should check, there are four pieces of felt in the bottom ram ways that should be changed. They help keep the ram lubricated
and pull trash out of the bottom way. From memory they are 1/4" thick and 3/8" Dia.
The tapered link pins below the ram push out to the right as viewed from the front of the machine. I no longer remember if there
is a set screw but can check my pictures.
A problem with changing those is the shim pack that sets the clearance of the ram ways might be ruined and you will have to cut
new ones.
You've got a really nice machine there.
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I think I could remove the ram positioning lock down lever and way gib's and remove the whole ram by going strait up. Good to know about these felt pieces. I am not seeing much in the way of literature on these shapers on the web. Thanks for your thoughts!
 
Bob Korves said:
High in relation to what, exactly?
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madmodifier said:
The zero I set near the column side of the table where the ram is fully retracted.
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That makes perfect sense for the table to show High at the far edge opposite of where the ram protrudes and points me to the ram being the part that has the worn "guides."
My Thoughts are that "if" the table was originally parallel to the rams travel and is now High at the farthest point of travel compared to the closest point, i would think as the ram fully extends , the forward force is slightly deflected upward which caused the guides to wear on your shaper....at least thats my theory but then again im not quite sure on how they work but i do believe the type of cutter you use would have a part to play in this also....so take it for what its worth.

If im way off base would someone please explain where my theory fails?
 
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madmodifier said:
The zero I set near the column side of the table where the ram is fully retracted.
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Reference everything to the machined and unworn front vertical surface of the main casting. It is the only rigid unworn plane on the machine and is provided for exactly the purpose of being a reference surface, both at the factory and in the field. Comparing worn surfaces with worn surfaces is an exercise in futility.
 
Bob Korves said:
Reference everything to the machined and unworn front vertical surface of the main casting. It is the only rigid unworn plane on the machine and is provided for exactly the purpose of being a reference surface, both at the factory and in the field. Comparing worn surfaces with worn surfaces is an exercise in futility.
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Can you assist me with how I would sweep the table while using the main casting as a reference? I cannot see how you could check the table in the axis that the ram operates in from the main casting as it is static.
 
Another issue to be considered is that the oil films between the ram and the ram ways will influence sag to some degree during use. That will make the ram effectively more rigid and with less play when moving. I have no idea how to measure that except by measuring 'in motion' cut heights vs static tool heights...
 
madmodifier said:
Can you assist me with how I would sweep the table while using the main casting as a reference? I cannot see how you could check the table in the axis that the ram operates in from the main casting as it is static.
Click to expand...
Something as simple as an accurate square held vertically against the main casting and on the table top in line with the ram and used with feeler gauges to measure any gaps could be used to check for relative droop/rise of the table top.
 
Here is the main body of the shaper. The ways of the vertical column are flat on the surface plate with the top of the casting facing us.
On either side there is a line of five threaded holes for mounting the top plates ( gibs) to hold the ram.
Either side of the hole patterns are the scraped surfaces that the top plates mate to.
On my machine these surfaces were out of plane by about one thou.
Those top plates are hardened. Mine have warped some, probably during the hardening process, but they should pull down when
mounting. I will later consider grinding them true.
The inner ways where the ram runs shows the four holes for the felt. Those measured 0.410" Dia. and 1/8" deep.
The figures I gave from memory in post #20 were wrong.
IMG_9482.JPG
 
Richard King is still feeling poorly, but he was able to look at Schlesinger's book "Testing Machine Tools", where he found the spec for the geometry of the ram of shapers. Page 87, fig. 5a, "Movement of ram parallel with work table (table rising at front) 0 to 0.015mm per 300mm (0 to .00075" over 12")" That is a different spec than I guessed earlier (in post 15 above), my guess was .001", .00025" more.
 
As one who's been there and was tempted by the same "fix" I just want to reinforce the caution all those before have advised. When I first went through the old Atlas 7b I acquired it was more like an archeological dig than the quick clean up I thought I was doing. Every new section I went to had a new odd fix that was applied sometime in its murky past. Along with damage done by somebody who either didn't know what they were doing as they were adjusting the stroke or forgot to take something lose before they tried to adjust it. Badly bent and scored gibs, bent lead screw, added shims to one side of the ram and on and on.

Each one of these intricate machines has its own ideosyncracies of adjustment and operation. Once I got the shims on the ram sorted my most wear was retracted, with almost no wear fully extended. It's also really hard to lift the ram at the end of travel because weight and drag from the mechanism. It helped to back off a bit by counter rotating. The rotating base to the vise was somehow warped. Fixed it and realized I didn't really need it. The jaws on the vise were warped, so replaced them. When I would have deviations in a surface cut I realized it was from play in the cutter head feed moving over time so installed a couple of gib locks and cured that. I'd also get screwy deviations when I'd not tighten all 8 bolts on the knee after adjusting it to height.

Bottom line I was glad I didn't just go with my first inclination and do a skim cut on the table when I first started using it.
 
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