Author Topic: X-2 Mill Problem, When is" In Tram" NOT in Tram  (Read 10315 times)

Offline 75Plus

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X-2 Mill Problem, When is" In Tram" NOT in Tram
« on: November 12, 2010, 02:49:13 PM »
I started to make a copy of Bogs tramming tool. First I trammed the mill to within half a thou over a 9.5" range using the conventional method. Next I clamped the work piece in the vise and, using a fly cutter, ran a clearing cut. I noticed that the cut seemed to deepen as the end was approached. Pulled the stock and miked it. Sure enough the piece had a .004" taper. I pulled out the tramming tools again and determined the tram was still dead on. Thinking that I had possibly not leveled the piece in the vise I tried another cut. The result was the same. I removed the vise and reinstalled the tramming tool into the spindle. I am using a finger DTI that reads in .0005" increments.

I started with the table shifted full left. I set the DTI to zero and started moving the table to the right. For the first 4 inches the needle did not move. At 5 inches the table had risen .0006", at 6 inches it was at .0015", at 7 it was .0024", at 8 it was .0032" and at 9 it was slightly over .004".The "Y" and "Z" gibs were locked through out and I locked the "Y" gib at each reading.

I have come to the conclusion that half of the table is wedge shaped and needs to be trued. Now to find a surface grinder to do it.

Thinking back, I found this problem when the mill was still in warranty I just did not recognize it. I had attempted to tram it by using the DTI directly in the spindle and ran the table past it. I found tramming instructions that left the spindle centered and took measurements at the ends of the table. This took the taper out of the equation. In the future I will use both methods as soon as I get a new mill.

Offline Brass_Machine

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #1 on: November 12, 2010, 03:20:26 PM »
Good catch.

How do you plan to fix it?
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Offline 75Plus

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #2 on: November 12, 2010, 03:37:57 PM »
Good catch.

How do you plan to fix it?

Eric, A 'Good Catch"?  :med: It would have been if I had recognized the problem when it was still in warranty.  :hammer: :hammer:

I hope I can find a job shop that can put it through a surface grinder. I am reasonably sure the bottom, the dove tailed side, is true as I have fairly smooth travel for the entire length of the table.

Joe

Offline Brass_Machine

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #3 on: November 12, 2010, 03:42:39 PM »
Ahhh... but you DID catch it. A lot of people wouldn't have.

Eric
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Offline kwackers

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #4 on: November 12, 2010, 03:53:43 PM »
In the U.K you could still take it back, goods have to be "fit for purpose" regardless of the length of warranty offered. In this case the fault is in the manufacturing so as long as it was out of spec you'd have no problem.
You don't have something similar over there?

Offline 75Plus

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #5 on: November 12, 2010, 06:04:15 PM »
Unfortunately there is no "fit for purpose" warranty that I know of.

I removed the table and made some measurements to try and determine where the problem actually resided. The overall thickness was .005" greater on the left side (end) than it was on the right side. I then measured the portion above the dovetail and found the same gain end to end. I take this to mean that the top is where the error is and would be the easiest place to rectify it.

If anyone has another idea PLEASE step up.  :scratch:

Joe
 



Offline Bolster

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #6 on: November 12, 2010, 08:29:20 PM »
New here, but interested in any attempt to tram a Sieg. I'm floored you were able to get it within a half thou initially (tilting wedgie table aside).

On my X3, I'm within about .002 all around, but at this point if I add even a half thou shim, it overcorrects. So I would love to know your secrets to getting your initial tram so right-on. Any sanding or scraping involved?

For me, my big learning moment on tramming my Sieg was that sweeping the table was a secondary test. The primary test was using the Z axis and a DTI against an angle plate. Because a bad tram can look OK with the table-sweep method, if the head is tilted to compensate.

Back to your problem: if resurfacing the table is not in the cards, perhaps a replacement table is? I believe Little Machine Shop has (or had?) replacement tables for Siegs.

« Last Edit: November 12, 2010, 08:31:08 PM by Bolster »
a.k.a. Delmar O'Donnell, bona fide soggy bottom boy

Offline picclock

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #7 on: November 13, 2010, 02:56:59 AM »
Hi

So it sounds like that if you measure the table height directly under the spindle, while moving X it varies ?

Cos if it does then you could just mill the surface of the table to make it true.

Sorry if this sounds stupid but I'm pretty new to this.

picclock
Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Offline Bogstandard

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #8 on: November 13, 2010, 05:36:35 AM »
Someone with a much larger mill should be able to face it for you either with a flycutter or large facemill, if they are good, they should be able to get at worst to 0.0005" out, or a machine shop should be able to regrind it perfectly flat.

Of course it depends if the table has been hardened, if it has, then grinding is the only way, but if it is a small 'hobby' type, then it should be fairly soft.
 
Find a 'one man band' jobbing type of shop, they are usually a lot cheaper than a production shop, as they are geared up to do one offs.

This is when having friends nearby can help.


Bogs
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Offline Brass_Machine

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Science is fun.

We're all mad here. I'm mad. You're mad.

Offline Miner

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #10 on: November 13, 2010, 02:47:26 PM »
75Plus,
I can certainly understand how you feel. I bought a 3/4 sized Bridgeport clone mill with a 32"x9" table and due to the ammount of work I was doing at my job didn't have time to really check out this machine till after the waranty was finished. The first time I trammed the head I found that the table must have warped after the grinding step and the table had a fairly consistant 4" wide low spot the lenth of the table of around .0015. That's not much but I decided to have the table re ground at a proffesional shop. This would have cost me about $400. I removed the table and drove 3 hrs. to this shop. Once they had it up on the grinding table and supported on super accurate ground straight edges on the bottom of the tables sliding surface they also found that the table had also twisted by .002 end to end. This would have to be corrected before re grinding the top surface of the table. To do this they figured that the table would need to be hand scraped to the female dovetail. Price? around $2000 and they would need the whole mill. This machine weighs over 1100 lbs and requires me to fully disassemble it to remove it from my shop. I'd then have to move it 150 miles to the re grind shop and reassemble. Hand scrape, regrind the table top, Disassemble, Haul it home another 150 miles, Move it back into my shop and reassemble. My table still has the low spot in it and I guess I'll have to live with that. Maybe someone else who buys a new machine can learn something from our mistakes.

Pete 

Offline Davo J

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #11 on: November 13, 2010, 07:44:55 PM »
Your not alone with your table issues.

I bought a HM52 (Grizzly3617 over their) about 4 years ago and the first one had a tapered table 0.1mm end to end. I tried to get it ground locally at manual machine shops and cnc machine shops and told them I would deliver the table degreased and clean and no time limit, but everybody said they only do work for companies?
Because of this I then went back on warranty and they delivered a new mill but this time it had a warped table 0.1mm up on the left and 0.2mm down on the right. They tried every other one in stock up and down the east coast of Aus but they where all the same (green castings).
They had just received a shipment of new mills from a different manufacturer with hardened tables to eliminate this problem . I then had to pay another $1000 for one of their new mills because it had a DRO fitted when I already had a DRO that I bought but they would not budge and take it off.

After having this mill for 2 years I am sorry I even got it with all it's other problems, the only thing going for it, is it has a strait table.lol

Dave

Offline Miner

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #12 on: November 15, 2010, 11:46:56 AM »
Dave,
To add to this list of horror storys I also have a Seig C6 lathe with the rear mounted mill that I bought from a company that went out of business very shortly after I bought it. The top surface of the cross slide was ground with a twist of over .0025 in it in two directions. The casting didn't warp as the dovetail checks out true. The supplied tee slotted milling table did warp, and the tailstock points uphill by over .009 in 2" I quit checking anything else at that point as my blood pressure couldn't take much more. I can rework the defects and I fully understand this equipment is built to a price level but a few simple quality checks at the factory could have save me a lot of work.

Anyone buying a new lathe or mill would do well to read this whole thread and buget some extra money for at least a .001 reading dial indicator to check out their new equipment as soon as they get it.

Pete

Offline Bolster

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Re: X-2 Mill Problem, When is" In Tram" NOT in Tram
« Reply #13 on: November 15, 2010, 12:08:22 PM »
Allthumbs said (in other forum):

Now, for a bit of explanation. Imagine a column tilted 10 degrees left and a head bolted on with a 10 degree right tilt. If you only did the quill test, it would appear the mill is aligned. Then, when you ran the z axis down the bit would wander to the right. This is why the column must be aligned before the head.

So true.
a.k.a. Delmar O'Donnell, bona fide soggy bottom boy