Mounting Plate.

[BaronJ]

Hi Guys,

First, thanks for the birthday wishes, the banner was a complete surprise :U

I've known that the head on my mill nods, for quite some time, and rather than strip the head and column off the machine, in order to fit shims under the bolts, I've decided to make a mounting plate on which to mount my new precision 90 mm milling vice.

My theory is that by making a plate that fastens securely to the mill table, and then by fly cutting the surface of the plate, that it will be truly parallel to the head. I'm aware that it may only be correct for a limited amount of head movement, but it has to be better than the three thou across the width of the table.

I've done a full size drawing of the plate and the four clamps for securing the vice to the plate. The steel plate is 12 mm thick and 160 mm X 220 mm, with drilled and tapped holes for M6 cap screws. I propose to simply glue the drawing to the plate and use it for marking out. I will place a piece of bar underneath the plate to accurately locate it on the mill table, so that when I come to take it off I can replace it and the vice will remain square to the table.

If anyone can see a flaw in this scheme, please shout out. :):):) Thanks:

341276

[Stustoys]

Happy Birthday.

I'm not so sure that's going to change much, unless all you're going to be doing is making large parallel blocks. In fact at first thought for most things you're making things worse... but then I guess its easy enough to take it off if it doesn't work. The mill head will now be trammed to the vice... but it will still be out in relation to the Y* axis(which is I assume what you are really trying to get around).

Well I shot.. did I hit anything?


Stuart

*and possibly Z, depending where the tram error is

[KBs PensNmore]

Happy Birthday Baron J. The theory of it sounds excellent, but before you go to far, I'd be inclined to do a test, fly cutting, as the head is slightly out, depending on the width of cut, you will end up with hollows (waves) going across your plate. What type of mill is it?
Kryn

[Anorak Bob]

Birthday greetings BJ.:U

From the size of the bolt holes I imagine the head of the mill doesn't require a block and tackle for removal. Would there be less rooting around scraping the mating surfaces of the head and column into alignment? My suggestion obviously flops into a hole if the column is round.

BT

[Stustoys]

Hi BT,

Yourself and BJ seem to be assuming the nod error is at the column/base joint(I'm sure we have a better name for it than that.......interface? ). I think it could be one of three other places(or all of them ;) )


My suggestion obviously flops into a hole if the column is round.

Why?

Stuart

[Ueee]

Happy Birthday.

I'm not so sure that's going to change much, unless all you're going to be doing is making large parallel blocks. In fact at first thought for most things you're making things worse... but then I guess its easy enough to take it off if it doesn't work. The mill head will now be trammed to the vice... but it will still be out in relation to the Y* axis(which is I assume what you are really trying to get around).

Well I shot.. did I hit anything?


Stuart

*and possibly Z, depending where the tram error is

I agree Stu, as if you are feeding with the X you will be fine, but as soon as you feed with with the Y you have problems, same with the Z.

[Anorak Bob]

Hi BT,

Yourself and BJ seem to be assuming the nod error is at the column/base joint(I'm sure we have a better name for it than that.......interface? ). I think it could be one of three other places(or all of them ;) )


Why?

Stuart

Stu, I have absolutely no idea of what BJ's mill looks like. I assumed :) that the problem was the interface between the head and column not the column and base because Baron said the mill nodded. Heads nod.

BT

[Stustoys]

Stu, I have absolutely no idea of what BJ's mill looks like. I assumed :) that the problem was the interface between the head and column not the column and base because Baron said the mill nodded. Heads nod.

BT
hmmm I maybe reading things into the post that weren't there :D

[BaronJ]

Hi Guys,

Thanks for all the good wishes. :U:U:U The kids have been over and brought my granddaughter to see us. Lots of chocolate too. Yummy. :)

I will take some photographs later and post them. In the meantime, the mill is the square column construction. Its the column that leans very slightly forward, or I assume that is where the lean comes from. If I use the tramming tool I can set the head to be spot on in the X direction. But if I turn the tramming tool through 90 degrees and check in the Y direction, I get about 3 thou deflection. This doesn't change if I lock the head gibs. Unlike the X axis. So when I check that I do it with the gibs locked.

My theory is if I now use the Y traverse to face the plate then it should be parallel to the head. I only need to machine a strip slightly over 90 mm wide and 220 mm long for the vice to sit on. As it happens my fly cutter has a 92 mm swing, so I would need to use the Y traverse to do the facing.

I hope I've got it right. I know that I should really take it all apart and put shims in, but its far heavier than I can manage.

[Michael G]

I don't think that is going to work as you think. If you mount a plate and machine it with a fly cutter you will get the new surface square to the axis of the spindle but as Z is now not perpendicular to X and Y, you will get a saw tooth effect as you traverse the cutter to do subsequent passes (assuming you traverse along the long axis. If you traverse along the short axis you will get a series of scallops parallel to the existing table).

341289

The only way to fix the problem is to make it such that all three axis are perpendicular to each other - whether that be shimming or removing some material.

Michael

[cba_melbourne]

Hi Guys,

Thanks for all the good wishes. :U:U:U The kids have been over and brought my granddaughter to see us. Lots of chocolate too. Yummy. :)

I will take some photographs later and post them. In the meantime, the mill is the square column construction. Its the column that leans very slightly forward, or I assume that is where the lean comes from. If I use the tramming tool I can set the head to be spot on in the X direction. But if I turn the tramming tool through 90 degrees and check in the Y direction, I get about 3 thou deflection. This doesn't change if I lock the head gibs. Unlike the X axis. So when I check that I do it with the gibs locked.

My theory is if I now use the Y traverse to face the plate then it should be parallel to the head. I only need to machine a strip slightly over 90 mm wide and 220 mm long for the vice to sit on. As it happens my fly cutter has a 92 mm swing, so I would need to use the Y traverse to do the facing.

I hope I've got it right. I know that I should really take it all apart and put shims in, but its far heavier than I can manage.

In theaory, your very first job is to make sure the columns vertical dovetails are perfectly orthogonal to the mill table. I had to do on my Sieg X3 mill too when I bought it, you cannot expect this to be right from factory on such cheap machines. I found the interface between the mill base and the column was not flat - at the factory someone had used a hand rasp to tram the column.

In practice, you probably will find that before you can tram the column you need to make sure the dovetailed part that slides up/down the column and where the mill head attaches to is properly fitted. Again in my case, the tapered gib had been fitted at the factory with a rasp. Only once that is done can you easily tram the column. Put an accurate square on the table, a magnetic DTI base on the dovetailed part that slides vertically on the column. with the tip of the DTI sense the vertical edge of your square whilst cranking the head up/down. Do this interleaving for x and Y axes. Either scrape or shim the interface between base and column until its right. Instead of a square you could make a cylindrical square on your lathe, provided its properly aligned not to cut taper. Or use an angle plate, but turn it over 180 degrees for each measurement to make first sure its really an accurate 90 degrees angle plate.

Next step, you need to make sure the milling head is mounted orthogonally to the dovetailed plate that slides up/down the column. For that you put the DTI mag base onto the milling table, and measure in x and Y that the quill is orthogonal to the table. Scrape or shim where the head mounts as necessary. Of course, if you have a swivelling head, you first have to make sure the swivel axis is parallel to y on the table surface and orthogonal to X on the table surface.

Before starting, of course make sure the table x and y dovetails are clean and properly adjusted, slightly to the tight side.

[.RC.]

This is probably an unsuitable idea as you said the mil is too heavy for you to disassemble it yourself. If you are unable to scrape the base to the column, you could always instead of making a sub plate for the vice, make a sub plate for the bed/column interface and longer bolts..

[Stustoys]

, you could always instead of making a sub plate for the vice, make a sub plate for the bed/column interface and longer bolts..
Now this I like. Assuming the error is at.the base/column. make a plate to suit, machine itas planned above, turn 180deg, bolt in place, job done(well ok, in theory job done).You should at worst be a lot closer and as RC says it.would.be easier to.tweek from.there.

[Ueee]

I don't think that is going to work as you think. If you mount a plate and machine it with a fly cutter you will get the new surface square to the axis of the spindle but as Z is now not perpendicular to X and Y, you will get a saw tooth effect as you traverse the cutter to do subsequent passes (assuming you traverse along the long axis. If you traverse along the short axis you will get a series of scallops parallel to the existing table).

341289

The only way to fix the problem is to make it such that all three axis are perpendicular to each other - whether that be shimming or removing some material.

Michael

That was what i was getting at, but with drawings it makes it easy to see.....

[BaronJ]

Hi Guys,

I promised some pictures of my mill.

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At the moment I've got the mill set up to cut out a 10 mm wide by 10 mm deep edge in a short length of 20 mm thick by 50 mm wide mild steel bar. I need these to hold down the new vice. I'll saw them to width later.

[BaronJ]

I don't think that is going to work as you think. If you mount a plate and machine it with a fly cutter you will get the new surface square to the axis of the spindle but as Z is now not perpendicular to X and Y, you will get a saw tooth effect as you traverse the cutter to do subsequent passes (assuming you traverse along the long axis. If you traverse along the short axis you will get a series of scallops parallel to the existing table).

341289

The only way to fix the problem is to make it such that all three axis are perpendicular to each other - whether that be shimming or removing some material.

Michael

Hi Michael,

Your drawing has me a little confused. :no: Easy to do nowadays. :)

I can see the effect that you are getting at in the top illustration, and I agree with you. Essentially that is what I am getting now However in the middle sketch, if I used a large diameter cutter and fed using the Y axis, wouldn't the scalloping be aligned the other way ?

Thinking about it, a shim under the back edge of the mounting plate would also have the desired effect. It would leave a small gap between the plate and the machine bed though.

[Michael G]

Yes, the scallops would be the other way. I tried to show that with the dotted line but it was just a quick sketch so probably was not as clear as it could have been. Shimming the mounting plate is probably the easiest way to go. At least that way you can get the axis square and see whether further work is warranted.

Michael

[BaronJ]

Hi Michael, Guys,

Now I can see where you were going. I'll put some shims under the back edge of the plate and see just how much tilt I need to get in order to square things up.

I've made the plate and cut a piece of bar to go underneath to ensure that the plate can be put back in the same position after it has been removed. I've taken photographs of the chunk of bar that will be cut to make the hold down clamps for the new vice. I'm cutting the step with the fly cutter. I ground a new tool bit with a flat face, like a left hand knife tool. I'm taking a 10 mm wide sweep with a 1mm depth of cut. In the picture I've about 4 mm left to go. The other pictures show the new vice just sat on the plate so you can see how it all goes together.

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Sorry about the spring clamp. I use them to hold a perspex sheet to stop bits of metal flying all over the place.

[BaronJ]

Hi Guys,

I got the block finished, just need to cut it up into chunks and drill for the bolts.

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Now that I've got the mill cleared of the vice and cleaned, I've been doing some measuring up. The tram in the X direction is just about a thou out measured at the back of the table. If I now move the table back towards the column, so I am taking a reading in the middle, the right hand indicator moves about a half thou. If I now come to the front of the table, the right hand indicator reads 2 thou. This suggests to me that the table is very slightly twisted. If I rotate the tramming tool through 90 degrees, I get the expected 2 thou which gets less as I approach the right hand end of the table and a thou more if I go to the left end.

I need the mounting plate to support the vice and I thought that I could use it to correct the small errors in alignment, now I'm not at all sure. :no:

[Stustoys]

Thats may well be good news.
If the error is above the Y ways your plate may improve things.
But you're shooting in the dark.
Stuart

[BaronJ]

Hi Stuart,

I was discussing this problem with a friend last night and going over what I had done and the measurements. He has suggested that its unlikely to be the bed that is twisted and that it might be informative to remove the bed and cross slide in order to examine the base and dovetails. We loosened the gib on the cross slide and the tramming tool indicated the the bed dropped about 3 thou. After we reset the gib the bed returned to the old reading.

I think that I will finish the mounting plate and the securing clamp blocks first and then pull the thing apart.

[Michael G]

Sounds more and more like there is a casting in there that has not been machined square. I'd be finding someone with a larger mill and possibly taking a strategic skim or two to get things back to the way they should be.

Michael

[BaronJ]

Hi Guys,

Well I've finished the clamps and fastened the locating bar to the underside of the mounting plate. Fitted the plate to the mill table and got the vice mounted. I've trued it up and nipped everything up tight.

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A friend of mine is going to come over at the weekend to give me a hand strip the table off the mill so I can inspect the ways, though at the moment I'm not at all sure about what I'm going to do about whatever I find under there.

[KBs PensNmore]

Nice work on the clamps and plate. I took my table off and it's about 10 thou different from on end to the other, and about the same on the base, making it hard to set up the gibs accurately. Hope it not the same on yours!!!
Kryn

[BaronJ]

Nice work on the clamps and plate. I took my table off and it's about 10 thou different from on end to the other, and about the same on the base, making it hard to set up the gibs accurately. Hope it not the same on yours!!!
Kryn

Hi Kryn,
Thanks for the compliment. :)
I won't find out until after the weekend when the machine will be stripped down. Fortunately I do have a friendly engineering works a few miles away that have said, to let them have a look at things. At least they have the capability to do things that I have no hope of doing. They are a good bunch of guys.