Gallery, Projects and General > How to's
Milling machine tram tool
bogstandard:
So after last nights camera fiasco, here I am again, burning the midnight oil. I had to work later tonight to try to catch up because I didn't get it done yesterday.
Went into the shop, turned on the mill, and everything was as I had left it, everything centred. So a quickie start.
First job, drill a hole right thru the bar. This is for the spindle holding bolt and I used a clearance hole for 6mm. This is a bit confusing here, dual measurements, but I told you I had to do some bits in metric.
I then followed it down with a 3/8" end mill. After a time using your machines, you get to know if it will cut accurately or not. I know that this will be an accurate cut. Maybe you could leave the spindle until you have cut your hole, and then trim it down to fit the hole minus 1 thou.
Not really the ideal, using a drill chuck to hold the cutter, but I know my chucks, and this one definitely cuts with no runout. My larger one would cut 0.002" oversize. Get to know your tooling, and you won't go far wrong.
This went to a depth of about 3/4". If you remember, the spigot was only 5/8" long. I don't want it to bottom in the hole, but to be pulled down tightly onto the formed shoulder where the shaft meets the spigot.
Next job, measure the diameter of the dial gauge holding shank. Near as dammit 8mm. You will have to measure yours for the size of drill you require.
Before drilling the gauge mounting holes, I did a quick check for fit of the spindle. By eyeball, it looks very close or even spot on, but as usual I am not trusting my eyes. Only when it is on the lathe will it show if it is out or not.
So I then got back to drilling the holes in the required places. After centre drilling, I put a 6mm down thru the bar, followed by a 7mm, then the final 8mm. If you carry out this method, of coming up to size on a hole, the hole usually ends up spot on size. The reason being, only the first hole drilled relies on cutting the middle part of the hole out, so if the drill is ground slightly out, you can end up with holes of all shapes and sizes. The following sizes of drills are cutting a lot less material than if going straight in, and also no tip to throw it off line. My hole sizes ended up spot on, a nice snug fit.
So that was the top face finished with. The bar was turned the other way up, recentred and an end mill used to put a recess in for the spindle holding bolt head to fit into. If you remember, this bar is 1.5" deep, so I went to a depth of 1/2". This left an uncut middle to the hole that is 1/4" thick, top to bottom, plenty strong enough to take the strain of a real tight bolt.
So while it was this way up, I took the opportunity to cut a 3/16" deep recess into the bottom face. This is to allow the bar to sit better on the table when measuring without having to worry about dirt and damage under the whole length of the bar. The final faces of the datums ended up at around 1" long by 5/8" wide, with the gauge tips protruding in the middle of the face.
Now back on the bench, after all holes were given a nice clean chamfer and all edges deburred with a scraping tool. Plastic tape was then put over the datum faces, to protect them during the next machining operations.
The next job was a straight forwards slitting cut for making the gauge clamps, one at either end.
So what is the correct place for the clamping bolts?
Measure up your gauge like this, mine were 3/4" long, measured to where the lead in taper starts. Half that figure = 3/8"
Measure from the edge of the hole to the end of the bar, half of 1/2" = 1/4"
3/8" down, 1/4" in. I didn't blue up and mark out as I don't want scibe lines over the finished product.
The bar was remounted into the vice (with new tape on datum faces), and the hole positions found using my edge finder.
I used 5mm cap screws instead of the shown 6mm. The 6mm looked way too large.
So a tapping size drill was put right thru, followed by a clearance drill, but only until it reached the saw cut. The recess for the bolt head was then put in.
After tapping the rear side, and after another deburr, the block was finally finished.
Now the two main parts can be assembled together. Using hi strength Loctite (clone) on the spigot and holding bolt, everything was given a good tighten up. This is now ready for when I can get back onto the job tommorrow, and true it all up.
Another late night.
Bogs
Stilldrillin:
Another crackin` episode John! :clap:
Keep `em coming...... :thumbup:
David.
sbwhart:
Superb rite up John
:clap: :clap: :clap:
Stew
Darren:
As usual a smashing write up John,
It's a wonder you never took up teaching, you have the knack. :thumbup:
bogstandard:
I have a rather duff right arm, and this morning, they drained all the blood out of my left one. Does this mean I am classed as harmless? :lol:
Jammie doughnuts, here I come. :clap:
The loctite has set, so now I can get it onto the lathe to true it up.
First off, I checked the runout of my faceplate. 0.001", normally that would be acceptable, but I want it better for the precision I am about to try to achieve.
So I put on a 2 thou cut, and sent the tool on a 40 minute journey. :med:
While the faceplate was being skimmed, I made a quickie set of clamps to hold the tramming tool to the plate.
So the plate was finished, and when checked, no runout.
This pic also shows a good example of the casting effects. Notice the shiny bits, that is because the casting was thicker in those areas, so that area cooled down a lot slower, and so ended up with a much finer chrystaline structure. You learn something new every day on Maddmodders. :mmr:
Using a technique very similar to one Bernd showed the other day, the trammer was gently pushed against the faceplate, with a piece of paper under the datum faces, to prevent damage. :thumbup:
While it was in position, I fitted the quickie clamps to hold it against the faceplate, again with pieces of paper to prevent damage.
The DTI was now swung into use. I first trammed across the top face, to see if the paper was causing any problems. It was spot on. So I then concentrated on the spindle. By gently tapping with a lump of nylon bar, I gradually moved the trammer to a zero runout position and then locked everything up tight.
So now was the time to see if my hard work was in vain. You guessed it, 0.0035" runout. :scratch:
So it does go to show, if you think you are making it accurately, it just might not be so. I expected this and it was the reason I kept saying that it needed to be mounted on the lathe for final tuning. It only had to be a minute amount out of vertical, and by the time it reached the end of the spindle, that error would be multiplied many times over.
The fix was dead easy, just gentle skimming up, and while I was at it, I reduced the spindle diameter to a very useable 12mm. Now it was truly spot on, and I was a happy bunny. :ddb: :ddb: :ddb:
WE NEED BUNNIES INSTEAD OF NANA's
So what do you do with it now?
Well the first thing was to fit the gauges, and put the datum faces down onto a perfectly flat surface. You could just move the 0 dial to line up with each finger and that would be it. But I go a little further and and by moving the gauges up and down in their locating holes, I try to get the dials showing zero at the top. It just looks neater. But also make sure the tiny dial measures the same as well.
So how do you use it?
Just put it into your chuck (a collet chuck would most probably be a little more accurate, but I know this one is OK).
Bring the tips down until they are resting on the table and are moving the dials.
Then just adjust the mill head until the dials show the same figure, it need not be 0, it can be anything, 8 or 3, as long as they are the same (including the little dials).
Swing it thru 90 degrees and you can tram the Y axis as well using the same procedure. If you are unlucky, 5 minutes total time.
Once the needles are at the same setting, you have now trammed the head on your mill.
As you can see, and as I said, my head is perfectly in tram. I should know, I used my own little tramming tool to do it.
A lot easier than trying to use a clock on the end of a bar, and then attempting to swing it thru 180 degrees to take the next measurement ----- and so on until you eventually get it right.
Little and large trammers.
The little one can now go to it's new owner.
So this little tool looks a pig to make, but in fact it is very easy, as long as you can keep things under control with fairly tight tolerances. As I said, the final lathe work will true it up a treat.
Total cost -- However much a pair of gauges are and a few bits of raw materials.
Your gain -- tramming now becomes a joy, rather than a PITA.
I hope you have enjoyed the post, and it gives you the inspiration to make one for yourself. You would never regret it.
Disappearing backlog Bogs.
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