[ti5m]

Hi guys.

I have had my SX2 solid column mill for about 6 months now and have just found out that my Y axis is not square with the X axis and was wondering what i could do to fix it if at all possible ?

I just got a new Glacern 4" vice for it and indicated it in to the X axis but when i went to make a square part i noticed that my Y axis was askew. I clamped a machinist square in the vice and ran a dial test indicator over it in the Y axis and its out by .1mm over 100mm travel. Which is quite bad really.

I got a new saddle from LMS to try and its still the same. It must be in the base dovetails possibly ?

Dose anyone else have the same issue or is it just my machine as i did a search here and came up with nothing ?

Any help is greatly appreciated.
Tim.

[SCzEngrgGroup]

If you think about it, a pure linear perpendicularity problem can *only* be caused by the saddle. Are you sure your square is really square? They often are not....

Regards,
Ray L.

[cyclestart]

Does pushing/pulling on the table change the indicator readings ?
There's enough geometry in a mill to make a person dizzy judging by the adventures of some of the hand scrapers posting here.

[ti5m]

Hi.

Yes pushing and pulling on the table dose change the indicator readings a little bit. In the area of 0.04mm or so.

I have some ultra precision 1 2 3 blocks i also put in the vice and they too show the same amount of error along the Y axis. And i have tried flipping my square over to the other side of the vice to rule out any inaccuracies in the square and it shows the mill Y axis is out in the same direction by the same amount also.

I put a piece of 100mm x 100mm wide alloy plate 10mm thick in the vice. Ran the mill down one side in the Y axis. Flipped the plate upside down and ran the mill over the exact same edge i just milled and when i start the mill cutter is JUST barely touching the freshly milled edge of the plate but when i advance the table in the Y axis the milling cutter will start cutting deeper and deeper as i go and by the time i reach the other end of the plate its cutting .1mm deeper. If the mill X and Y where square the milling cutter should be just barely touching the fresh cut edge all the way across the plate. Not cut deeper as the Y axis is advanced.

The vice fixed jaw is in perfect tram with the X axis. So anything milled in the Y axis should be square with the X i would have thought ? Providing two of the plates edges are perfectly in parallel. Which my ultra precision 1 2 3 blocks would be also.

I agree the saddle should be the only thing that it could be. But i now have 2 saddles that seem to be out in the exact same direction by the exact same amount and i cant see that would be very likely unless something else is to blame ?

Gibbs are all nice and snug. Stock lead screws so there is a fair bit of backlash which i think is where the table movement is coming from when pushing and pulling on it.

[ti5m]

Just found this which explains the exact thing that is wrong with my machine. glue-it.com --> Model Making

Seems i am not the only one after all.

[cyclestart]

push/pull = rock side-to-side to feel for any play in the gibbs but you've got that sorted.
Could anything be learned by dissasembling and rotating the saddle 180 degrees on the base ? I'm assuming the parts will mate this way but I'm not sure.

[mduckett]

Out of curiosity, went looking for some additional background and found these articles too:
Warco mini mill cnc conversion

and this which talks about possible software correction in Mach3:

http://www.cnczone.com/forums/bencht...0_degrees.html

--md

[109jb]

If mach 3 can't correct it, linuxcnc can.

LinuxCNC Documentation Wiki: Kinematics

[SCzEngrgGroup]

Out of curiosity, went looking for some additional background and found these articles too:
Warco mini mill cnc conversion

and this which talks about possible software correction in Mach3:

http://www.cnczone.com/forums/bencht...0_degrees.html

--md

That is another feature of Mach3 that is only half-baked, like the screw-mapping correction. The correction is not applied under all conditions, so it's really not usable. There have been several discussions of this on the ArtSoft forum over the years.

Regards,
Ray L.

[ti5m]

push/pull = rock side-to-side to feel for any play in the gibbs but you've got that sorted.
Could anything be learned by dissasembling and rotating the saddle 180 degrees on the base ? I'm assuming the parts will mate this way but I'm not sure.

That's not a bad idea actually. Yes i think the saddle will go on backwards. Think i saw someone else do it to help with installing Dro scales. I might give it a go and see what i find.

After reading that other thread mduckett linked too it seems like getting the saddle re-machined is the only real way to fix it. Only problem is it would cost me about $500 here to get done. Such is living in a remote area that doesn't have much in the way of machine shops to choose from. Those guys in the UK got theses done for 30 pounds which is crazy cheap.

[mduckett]

That's not a bad idea actually. Yes i think the saddle will go on backwards. Think i saw someone else do it to help with installing Dro scales. I might give it a go and see what i find.

After reading that other thread mduckett linked too it seems like getting the saddle re-machined is the only real way to fix it. Only problem is it would cost me about $500 here to get done. Such is living in a remote area that doesn't have much in the way of machine shops to choose from. Those guys in the UK got theses done for 30 pounds which is crazy cheap.

Once you are satisfied that you have the problem isolated 100% to the saddle, I would contact LMS and describe the problem to them in detail. I've found them to be very helpful and responsive. A part out of square that much should be considered defective, not sure if it is still in warranty but it would be worth a try. --md

[ti5m]

Ok. So i just tryed with the saddle and table installed backwards. Got the exact same measured result.Then i tryed installing my old saddle back on and got a .02mm error in the same direction ???? thats with the square clamped directly to the table and tramed in the X axis. Put vice back on. Tramed it up with the X axis. Clamped square into vice. Checked its tram with the X axis again to make sure its still straight with the vice jaws done up. Now i get a consistant .05mm error ?

This is very strange indeed. Why would i get a near perfect reading with square clamped directly to table but it get worse with the vice installed ? It should be exactly the same ? Unless the vice bottom is not perfectly flat and is titling diagonally to one corner ??? So anything mounted high up in the vice the error would get worse the higer you go ? Or its the mill table thats not flat and true. ( more possible ). Its a brand new Glacern 4" vice. It shoule be dead nuts straight and flat so i refuse to believe it could be the vice. More something in the mill.

I have been chatting with Chris from LMS about it and thats who sugessted i get another saddle for it in the first place. I didnt get the mill from LMS as i am in Australia. But i cant get parts here for it so i get them from LMS.

So the old saddle is .05mm out.
New saddle is .1mm out.

Here is a pic of the old saddle. Check out the dip in the fixed side Y dovetail.It looks twisted also when looking along it. The new saddle dovetail is flat but measures worse ???.

Attachment 222172
Attachment 222170

[ti5m]

I think i need a new mill. Something not SIEG and of much higher quality to start with i think.

[ti5m]

Just tried putting some layout dye on it just to see how much of the saddle dovetail was actually touching and got a bit of a surprise.

Attachment 222478

I wonder if this could be the cause of my out of square problems ? Looking at the gib on the other side of this it looks to be on an angle. Its adjusted out further on one end than the other.

Do you think i could install my other saddle and try using my mill to clean up and straighten out this dovetail with a 55 deg dovetail cutter myself ?

[Gregj888]

On my HF X2 most of the ways were about the same (including the column). I started by scrapping and a little sand paper lapping (so I could control where material was removed. Not completely done but close but getting close to 0.001" all directions on the table and X/Y are as square as I can measure.

If your gibbs are as flexible as mine, you don't have to do anything to them.

So if you are on a budget and have a surface plate, an old file, tube of Prussian blue and a couple of weekends... ;-)
Greg

[ti5m]

S how do you scrape dovetails ? As these are not pictures of the ways. Its the dovetails that are out of wack. I think it can only be done with a dovetail cutter and another mill unless im misstaken ?

[Gregj888]

Dovetails can be scraped, but you need a flat that will fit into the area. I have the material to make the flat but haven't yet. Scraping in a dovetail - detailed - YouTube

Lot's of discussion about lapping, but I did a light lap using fine sandpaper. Sand side toward the side of the dovetail where I wanted to remove material. I set up a dial indicator to show movement as the piece slid, then took off material from the side to compensate. I did a light pass, planning to scrape to final shape later. Follow this link down a few pages for details Page 7 - this is not mine, but what I referenced.