Thread: The old "trimming the mill" question

I'm wondering if others like myself dont exactly understand the question?

Stuart

Stu. Thanks for pointing that out. It is a bit ambiguous and wishy washy isnt it. I have a link for anybody who is interested. This guy trammed his mill by unbolting the column from the base and inserting jamb nuts under the column flange and on top of the base flange so he could adjust each corner individually. The guy in the link had some success with it but I have some reservations about lifting the column above the base like that. Would it be strong enough?

http://www.homemetalshopclub.org/new...esentation.pdf

regards

Old Hutcho

ps: I did have a search of the threads but I cant find anything relative.

Hi Dean,

Thats how my lathe is mounted but the nuts arent between the cutter and the work.
I dont think much of the idea, I'd scrape it once I was sure that was the problem. Having said that...... if you only use cutters on the small side and didnt push things I dont see why you couldnt get by like that.....I guess it depends on how bad your tram problems are as to whether you can put up with losing rigidity to fix it.......

Not sure I like the way he went about making his parallels either but thats not my problem

Stuart

Originally Posted by Stustoys

Hi Dean,

Thats how my lathe is mounted but the nuts arent between the cutter and the work.
I dont think much of the idea, I'd scrape it once I was sure that was the problem. Having said that...... if you only use cutters on the small side and didnt push things I dont see why you couldnt get by like that.....I guess it depends on how bad your tram problems are as to whether you can put up with losing rigidity to fix it.......

Not sure I like the way he went about making his parallels either but thats not my problem

Stuart

Hi Stuart.

How are you doing? Had a nice day, have you?

Now where were we?

Mixing Metaphors are a bitch, but?

Dean

Originally Posted by Stustoys

I'm wondering if others like myself dont exactly understand the question?

Stuart

I have got my hand up, but that is not unusual!

Dean

lol oops sorry Old Hutcho and Dean

Stuart

I didn't understand the question either, but that is by the by...

That method worries me - it sounds like the guy has a mill that is not suitable for doing the work he wants but he would be better off getting another mill. By supporting the mill column like that he is taking away support for the base of the column. Cast iron is strong in compression but weaker in tension. Using that method he has reduced the rigidity of the machine as well as made it more susceptible to breaking.

I know that if you are skilled some pretty amazing improvements can be made but from the presentation I get the impression that he lacks the background to know what he should and should not do.

Michael

I assume you have a round Column rf 30 type mill drill. Mine is pretty bad with I,d put shim under the cloumn or do as I do and live with it.

With regard to overall rigidity of any desktop mill, the connection between column and mill table is always a weak link. One could argue it is usually THE weakest single link. And that is before the modification made by Norm Berls.

Get me right, the idea itself is correct; this is indeed the only place where this type of mill/drill can be trammed. It is the execution that is bad and very wrong. Ideally the two mating surfaces should be scraped until flat and the quill is orthogonal to the table (yes the quill, not the round column). But few people will say scraping orthogonally it is worth the time for a mill/drill. If unhappy with the tramming, I would personally only file/scrape the mating surfaces roughly flat, and then insert as few and as thin as possible metal shims to tram. This is not a precision mill, it is essentially a coordinate drill press that can also be used for milling. Chris

Thinking about this a little more. If I was going to fix this, I think I would scrape both faces flat as is and than add a 10ishmm plate between them and do the alignment on that. (assuming added 10mm to the Z isnt going to be an isue).

Stuart

Originally Posted by Stustoys

Thinking about this a little more. If I was going to fix this, I think I would scrape both faces flat as is and than add a 10ishmm plate between them and do the alignment on that. (assuming added 10mm to the Z isnt going to be an isue).

Stuart

It doesn't really matter what you do with these machines, they will still have issues as precision mills because, well, they aren't.

If you want precision then the best thing to do is sell it to someone who needs a drill press with an X-Y table and buy a machine designed to be a mill.

Yes you can scrape the surfaces but that does nothing to fix all the other issues like lack of ability to hold tram in Z when changing height, column flex etc etc.

As for the adjustment method, well, no. I wouldn't do it. Shimming the joint is as much trouble as I think these machines are worth. If that doesn't fix the alignment issue, see previous comment. Gumtree is waiting.

PDW

Originally Posted by PDW

As for the adjustment method, well, no. I wouldn't do it. Shimming the joint is as much trouble as I think these machines are worth. If that doesn't fix the alignment issue, see previous comment. Gumtree is waiting.

While I pretty much agree with what you're saying.... I'd argue that it depends on a few things such as what the owner plans to use the mill for and just how bad the problem is. A light duty mill may meet his needs if the tram wasnt so far out he was getting 0.3mm steps. I'm not big on slims as I always seem to need one I dont have, but most I dont like the idea of two flat surfaces pulled down tight with a 0.010" shim under one end......
As I said earlier I'd want to be sure that was the problem first though.

Stuart

After reading all the way through that power point presentation, I still wonder why he didn't just tram the vise?

I got a bit lost with the adjustable parallels...

Ray

Originally Posted by RayG

After reading all the way through that power point presentation, I still wonder why he didn't just tram the vise?

I got a bit lost with the adjustable parallels...

Ray

I guess he just thought it was a good thing to do and enjoyed doing it. Maybe he will make money selling adjustable parallels. If a parallel is adjustable, it isn't parallel is it?

Dean