Tramming a Harbor Freight mini mill

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maddthom

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I am brand new to hobbyist machining, I've bought a Harbor Freight mini mill and a Morphron 7 x 14 mini lathe, I didn't have the money to buy anything better. A machinist gifted me a Mitutuyo dial test indicator to measure and loaned me a Brown & Sharpe test indicator, I have a couple of questions I hope someone can help me with tramming or squareness, and if I'm posting them in the right forum.

1. the mini mill, the head is not square to the column, I've gotten the column square to the bed(I think, see question 2) but do I need to shim the head? or does it matter that the head is canted about .02" / .5mm (I'm an American but its easier for me to use the metric system than fractions, the Mitutuyo is metric)

2. I think I've gotten the column square to the bed BUT when I turn the beds Y axis the needle on my indicator moves, to me it seems like the bed is tilting, also when I measure along the X axis I get different measurements from front to back, again its seems to me that bed between the T-slots isn't level/height or I'm I doing something wrong?

3. I understand that I have the cheapest machines but what kind of accuracy should I expect? Just adding a little context, I've taken both of my machines apart trying to get them completely square or am I trying to do something that is not possible?

4. I've looked but I haven't found a guide to tramming a mini mill or lathe, is there one? If someone knows were I could find one please give me a link, thanks

If anyone could help me I would greatly appreciate it, if any one has any tips, advice or links to tutorials I would love to hear it but thanks to anyone trying to answer my questions.
 
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Maddthom,

Please forgive my manners. I see this is post number One for you; I was remiss in offering a welcome to the forum.
Do give a thought of going to the "INTRODUCE YOURSELF & WELCOME NEW MEMBERS" forum
and telling us a little about yourself, and your new equipment.


Other than charter members of the deep-pocket club, many here started with smaller equipment than they sport today.
Most of us smile because we know the journey you are about to undertake. Assuming you stick with it, you will likely
upgrade and increase the size of your equipment over time. You may even fund the upgrades via producing some
gizmo on the equipment you have today (but that is an Entirely different topic).

With small equipment it can be harder to get great results without experience. An old salt can walk up to a mini-lathe/mill
and produce solid results. He knows how to compensate for what limitations and challenges which may exist in smaller equipment.
A person with less experience will INITIALLY produce parts of questionable virtue on mini-equipment.
But, as they master feeds and speed along with tool grinding, they eventually start producing good parts; don't get discouraged.

I cannot under-state how important it is to put a bit of sweat equity into inexpensive equipment. Often finishes on the equipment are a big rough, may have burrs which affect accuracy and trueness. You may find that things are just out of alignment (as you have). This can
force you to dive off the deep end into "metrology" to set your new equipment to "true".

Start out with easy metals, such as aluminum or brass. Steel, especially cold-rolled steel is tougher to get great results with initially,
and it may discourage you. Finding a source in your area for "non-mystery" metals is helpful too.

Best of luck to you.

Addertooth
 
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Thanks I really appreciate it, but I've seen those videos and that article and they didn't help. I've not seen anything about a tramming the head to the column, again my machines column is square to bed with the X and Y axis locked, the head is not square to the column, I could just shim it but you have to disassemble the entire head to do so then reassemble, measure and repeat but I don't know if thats the correct thing to do or if its necessary, does the canted head matter? The Harbor Freight mini mill has a tilting column, it has a single 32mm nut, T bolt and squash washer for tilting and that mounts to the base with 3 bolts, the bolts are in a almost straight line and it acts like a pivot point, I've seen someone take .5" steel plates and weld them into a L shape to mount to the base and column to it to make it more rigid but I don't have the steel or a welder. But thanks again.
 
I can be of little help on truing/shimming the head itself. I am not familiar enough with the model of mini mill you have.
Virtually all of the mini-mills of that family (harbor freight, Grizzly, etc) are made by a company called Sieg (or close clones to the Sieg). I know there
is a wealth of information out there for those models.

For some general rule of thumb, shims are appropriate IF the surface shimmed is static, i.e. does not slide on the shimmed surface. Any sliding or rotation on a shimmed surface tweaks the trueness each time it is moved. This is why the base of the column is a favorite place to shim. However, if the column is perfectly vertical, but the head is at a strange angle, I would be tempted to true the column face where the head attaches to the column, or true the face of the head where it mates to the column (you would need to figure out which of the two was mis-machined). But then, you are getting into the whole "you need access to a bigger mill, to fix your smaller mill" which is not always reasonably available.

As for error, "canting" I normally try to express the error in the impact on the part you are working on. If a 6 inch long part is 1/1000th of an inch thinner on one end, than the other end, I express the error as 0.001 over 6 inches. If something "looks strange", but cuts true parts (and flat cuts Without dishing), then there is little harm (other than to my emotions).
 
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I'm having fun just trying to set the machines up. I think, but I need to double check, that the head is canted to the right, not nodding, does that matter? But if it does, the guy that gave me the Mitutuyo indicator has a Bridge Port and told me to come anytime I need to use it.
 
And remember, a head is not nodding, unless it is locked and nodding. It is well understood the play in the gibs can make the head nod and cant until it is locked (tightened) in place.
 
Maddthom: If you can post some closeup pictures we can give some more detailed advice on what you might do to improve the situation
Cheers,
Mark
 
Welcome to the forum. You will get good answers to any question you might have no matter how simple the question may be.

If I understand what you have done so far is that you have squared/trammed the column to the table and now you are trying to square/tram the head to the table. I think that is the wrong approach. It doesn't matter if the column is square/trammed to the table. What matters is that the head is square/trammed to the table. That is what is important. The accepted way to do this is to place shims between the base of the column and the table.

Again welcome to the forum. The really knowledgeable people on here will help you get your mini mill dialed in.
 
mickri said:
If I understand what you have done so far is that you have squared/trammed the column to the table and now you are trying to square/tram the head to the table. I think that is the wrong approach. It doesn't matter if the column is square/trammed to the table. What matters is that the head is square/trammed to the table.
Click to expand...
With all due respect, it does matter if the column is square/trammed to the table. If it isn't, the head will not move straight up and down relative to the table, but will shift along the X and/or Y axes as it moves up and down. A long jobber drill, for instance, will not align with a starter hole made with a short center or spotting drill. The actual amount of offset might be inconsequential to the operator or the operation, but it will be there.

Tom
 
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