Tram of my mini mill and flycutting. What am I missing?

[Rimbaldo]

Hi!

I’ve just trammed my Sieg X2 cnc converted mill.

I’ve first removed the collumn and trammed the head to the collumn the best I could, by using the rollie’s dad method.

I then did the stiffener plate on the back of the collumn so I could correct the forward tilt the collumn had the best I could.

When using an indicator with it’s magnetic base attached to the spindle, and with the X length centered in the middle of the table (on 0 marking) , I turned it around the 4 corners and got 0 and 0 in front and back borders of right most side and 0 and 0.01mm in the front and back of the left most side.

There are two things I don’t understand:

First is: when instead of rotating the indicator (attached to the spindle with its magnetic base) around the table, where I get all four corners mostly right, if I adjust the indicator below the spindle and close to it’s center (as if it was an endmill) and I don’t move the indicator, but move the y forward and back to the edges of the table (12mm I think) I still see 0.03mm of forward tilt . Why this happens?

Second is:

When doint a test cut with a flycutter on a 55x55 mm aluminum block, on a vise in the center of the X, I noticed that the cut is clean, from left to right the needle of a test indicator remains still, but from front to back there’s a continuous inclination of 0.02mm in this 55mm block. i didn’t notice any concavities, it’s a smooth inclination.

I set the flycutter diameter (70mm) to pass over the complete length of the part, close to 140mm.

I got a ((((((( pattern untill the “back” of the flycutter, when the front had already left the part, started doing a ))) pattern, but as if it was another pass, removing that previous ((( pattern. So the “front” removed a little bit of material, than the “back” started removing again. Why did this happen? Shouldn’t the front and back pass of the flycutter be on the same level? Do I still have some left/right tilt? But if I have some LR tilt, why the indicator on the piece from left to right keeps at the same level?

Thanks for reading!

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[machinehop5]

This might help you https://www.tormach.com/blog/level-not-tram-mill/
Depending how square the Saddle (Y) ways are to the Table (X) ways from the Factory will effect tolerances of machining capabilities of your Machine.

[Kenny Duval]

It means a couple things.

1. Unless you are using a tenths indicator then it won't be sensitive enough to show you the error in spindle tram when you are close the center of the spindle.

2. Moving out any distance from the center of the spindle magnifies the error until you can see it on your indicator.

Now if the Z axis travel is square then that would indicate there is still some now in the head and that would be somewhere between the head and the column. Could be the gibs are a little loose or it could be error in the connection between the head and the Z axis slide. Ona machine this size you are likely going to chase your tail a bit trying to get that last little bit of error out of it.

[Rimbaldo]

It means a couple things.

1. Unless you are using a tenths indicator then it won't be sensitive enough to show you the error in spindle tram when you are close the center of the spindle.

2. Moving out any distance from the center of the spindle magnifies the error until you can see it on your indicator.

Now if the Z axis travel is square then that would indicate there is still some now in the head and that would be somewhere between the head and the column. Could be the gibs are a little loose or it could be error in the connection between the head and the Z axis slide. Ona machine this size you are likely going to chase your tail a bit trying to get that last little bit of error out of it.

Hi Kenny! Thanks!

I didn’t understand very well the first thing you wrote:

My indicator measures up to 0.01mm. I don’t have one that goes to 0.001mm. Is this precision needed?

When you wrote “show the spindle tram when close to the spindle” you meant spindle alignment to the x, or spindle alignment to the collumn? I measured from the spindle to the extremes of the x, maybe 26cms in diameter, so not close to the spindle.

Is it correct to mount an indicator around the outer part of the spindle and rotate it around the ways, or it must be mounted as an endmill, “inside” the spindle, through a collet, for instance?

[Kenny Duval]

No..what I meant is that if there is an error in the tram of the head if you indicate the table at a 1 inch diameter from center line of the spindle rotation the error may look quite small. However it you took that same indicator and moved it out to a 6 inch diameter from centerline of the spindle rotation the error would be magnified over that distance and produce a larger reading on the indicator. So a small cutter would have very little error when cutting but your much larger fly cutter would have more error at the cutting diameter. The same would apply to longer drills as well. The further the tool is from the spindle face or gauage line the more error in position of the tip would be created.

[Rimbaldo]

No..what I meant is that if there is an error in the tram of the head if you indicate the table at a 1 inch diameter from center line of the spindle rotation the error may look quite small. However it you took that same indicator and moved it out to a 6 inch diameter from centerline of the spindle rotation the error would be magnified over that distance and produce a larger reading on the indicator. So a small cutter would have very little error when cutting but your much larger fly cutter would have more error at the cutting diameter. The same would apply to longer drills as well. The further the tool is from the spindle face or gauage line the more error in position of the tip would be created.

Understood. That’s why big a big diameter fly cutter shows in it’s cut any misalignments.

I’ll check again the gibs and the spindle/collumn alignment...

Thanks!!

[Fastest1]

Or simply put your indicator on a longer arm to see the area to correct. Buy a piece of granite floor tile at your big box store, the thickness is very uniform as they use optical quality grinding. It will allow a bigger sweep area. A car disc brake works too.

Understood. That’s why big a big diameter fly cutter shows in it’s cut any misalignments.

I’ll check again the gibs and the spindle/collumn alignment...

Thanks!!

[Rimbaldo]

Or simply put your indicator on a longer arm to see the area to correct. Buy a piece of granite floor tile at your big box store, the thickness is very uniform as they use optical quality grinding. It will allow a bigger sweep area. A car disc brake works too.

Hi, thanks for all your answers. I decided to get a brake disk then, and it turned to be so much easier to tram x and y with the disk and an indicator mounted on the spindle.

So I put the disk centered in the table, with the spindle centered with the center of the disk and trammed all 4 extremes to 0. Rotating the indicator, it remained at the same position in a 360 degree circle. So far so good.

I clamped with a bolt a 52x59 mms block of aluminum directly to the table, centered on it, and faced it with a 12mm endmill and 16mm endmill (the thickest I got) and with the flycutter at 67mm diameter.

With the 12 and 16mm endmill, I got a perfecty square surface, left to right and back/front.

But with the flycutter, I still get perfectly square from left to right, but still I got a 0.04mm difference from back to front.

The surface of the block is smooth, there’s no concavity in any direction, but I still get (((((( at first, and when the cutter back starts passing over the part (from right to left) I then get ))))). This ))))) erases the previous (((((, and the final look of the part is not ()()(), but only )))))).

There’s still a really small tilt on the spindle to the collumn (there’s still 0.01mm tilt to the left in maybe 8cms height difference, and 0.015 tilt foward and the same height difference by the rollie’s dad method)

Could this small spindle/collumn tilt be resposible for this not squareness of my block’s surface and only final )))) pattern when using a large diameter fly-cutter?

The higher diameter I use on the fly-cutter the higher this small spindle tilt to the collumn will show it’s effect on the part?

Could the flycutter have a ...problem?

Thanks again for reading and helping!

[machinehop5]

Could this small spindle/collumn tilt be resposible for this not squareness of my block’s surface and only final )))) pattern when using a large diameter fly-cutter? Yes

The higher diameter I use on the fly-cutter the higher this small spindle tilt to the collumn will show it’s effect on the part? Yes

Could the flycutter have a ...problem? only if, it gets crashed by Operator...lol

Joking aside...I see in your photos the Machine is bolted to a steel plate or something.....it maybe possible the Base is being twisted a small amount by being bolted down. Loose the Front two Bolts (on Base) and see what happens when Tramming with your Test Indicator. The other problem that would cause want you've described is the Z Column is off to the Y Saddle Base.


DJ

[Fastest1]

You are getting there. On the other hand, one decent little crash and you get to do it again. I have lessened my desire for perfect flycut parts on a small Chinese mill and my amateur skills ;-) A simple brush with Scotchbrite will put a sheen on it.