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bedding down the lathe

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Marine Man

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Guys I need some advice here.

Recently I have changed lathes from an old Myford 7 to a pristine (I mean really pristine! - I know the history of this machine and the guy that owned it was a real perfectionist!) Myford Super 7.
It is mounted on a steel cabinet which is bolted to the concrete floor and the lathe itself is raised on steel riser blocks. When I was torquing down the holding bolts (Clock on the end of some 20mm round stock gripped in the chuck), the clock initially moved one hundredth of a mm on the last bolt. I released all the bolts again and shimmed it then torqued it down a second time with no movement of the clock this time. In curiosity I grabbed the end of the bed by hand and twisted it and got the same movement on the clock (one hundredth) only the clock did not return to zero when I released it. If I twisted the other way then it would return to zero.

I have checked everything and there is no damage to the bed and the lathe turns true on the parallel. My question is should I worry about this movement? I am begining to suspect that the cabinet might be a bit flimsy but I never thought I would get that movement on the bed by applying hand force. Any suggestions or advice would be very welcome. Thanks.

Paul
 

lazylathe

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Hi Paul,

Not being the foremost authority on this but it does sound like your bench is a bit
on the flimsy side.
Is it possible to upload some pics of the current setup?

Just for chatting sake... I have my ML7 mounted on a 4 inch thick concrete slab.
No movement there what so ever!

I also know that another member, machinetom, had his ML7 mounted to a very thick slab of granite.

Heavy and solid is the way to go!

Andrew
 

Marine Man

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Hmmm... that's what I fear too.
The guy who owned it before me had already reinforced the cabinet but I don't think its enough.

I'll get some pics of the setup and post them tonight.
 

lazylathe

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Cool!
We will be waiting for the pics! ;D

I made my own bench when i first brought the ML7 home.
Thought it was rock solid till i turned the lathe on and it vibrated all over the place...

If you are bored you can have a read through this post:
http://www.homemodelenginemachinist.com/index.php?topic=16122.0

There are a few pics of the completed bench.
I love it!!!

Andrew
 

Marine Man

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OK these pics are not the best and I have had to downsize them cos our internet is sooooo slooooow, but it should give you the idea!

The tray and cabinet is all 1/8th pressed steel and the longitudinal supports under the tray are 1/8th by 1 inch flat bar. The bad paint job is where the previous owner tried to reinforce it. Four 10mm rawl bolts hold the whole thing down to the concrete floor.

.... okay I am one of the computer illiterate chaps, so I am going to have to work out how to attach photo's to this. Bear with me....
 

chipenter

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What does it sound like and is there any vibration ? If you feel it is affecting the work produced then go for thicker mounting , the best I have seen is a 4x2x1\4 box section welded in a I shape .
best of luck Jeff
 

abby

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100th of a mm thats less than 1/2 thou , I wouldn't be bothered.
 

DanP

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Wow, you guys are starting to scare me. I have a Myford ML7 and have had for about 5years. It belonged to my Uncle who bought it new in 1958 and used it to make specialised camera parts for under water photography. I have never leveled it other than made sure it sits solid on it's base, a Myford cabinet which has several draws down one side and 2 shelves on the other. It seems solid, just sitting on my garage floor. I guess I better get a machinist's level and see if it's level and square. Like I said in a past post, I am a real newbie.
 

Marine Man

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No there is no vibration and it seems to be turning parallel ok Jeff, so I guess maybe I am being too fussy.
Its just I never expected to get any movement on the clock by putting hand force on the bed.

Thanks for the link on how to deal with photos - will work on it tonight.
 

Marine Man

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Now for the underside.
Also trying to figure out the optimum size for these pics. Apologies if they are too small.

Lathe supports.JPG
 

dsquire

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Marine Man

I see that you are getting the photos attached. Some of the guys use 800 x 600 for a photo size. Here is a link to a thread that uses that size.

http://www.homemodelenginemachinist.com/index.php?topic=15942.msg193986#msg193986

They are big enough to see the detail and small enough that they load fairly quick and can be seen on most browsers without being half off the page. If you have any problems just ask as someone will be happy to help. :bow:

Cheers :)

Don

 

steamer

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Some Displacement is normal, and expected even from hand pressure....the lighter the machine, the more movement.

Even a lathe is made out of materials that have a deflection curve and they spring out of the way when a force is applied.
As an experiment....put the normal tension on the drive belts, set a rod in the chuck and set the DTI to zero.....now remove the tension on the belts......I think you will be suprised! :eek:

Dave
 

MachineTom

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You did not mention if you shimmed the cabinet before bolting it to the floor. The cabinet look like the Myford made cabinet for the S7.

One of the odd(to me anyway) things about the Myford cabinet is that it had jack screws set between the risers on the cabinet and the lathe bed. Not sure if that was a factory idea or the PO doing. But it sure killed any ridgidy gained be the cabinet structure.

You could try this, loosen al the bolts from the lathe to the cabinet, shim the cabinet level, and make sure that the floorbolts are not twisting the cabinet as they are tightened. Then level the lathe bed with shims not the jackscrew typ thing.

On the other hand .01mm over 20" + is tighter than you can turn, bore or drill anyway.

 

Marine Man

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Thanks Guys for all the advice.
Took me a while to reply as I have been away and also waiting for the dust to settle after the HMEM change over.

I have decided to run with it as is for the moment. Cannot fault the machines operation and it turns true on the parrallel which is what I consider the most important.

I did what you suggested Dave and you were right - I was certainly surprised at the deflection I got after removing the belts!

Thanks for all the tips.

Paul
 
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