T-nuts…

[tmac1956]

All:

Using my mini mill/drill, I finally worked on some steel stock and made some T-nuts. My vise takes 3/8-18 bolts, but my rotary table takes 5/16″ bolts. So I made three for the rotary – the one on the end was some leftover material, but it worked out OK.

Yea – I know this is beginner stuff, but I thought I’d post a picture anyway.

Later,
Tom

[david pierce]

Tom,
The part looks great. Did you achieve the symetry by turning the part around in the vice?
david

[tmac1956]

David;

Yes – I took your advise on that one. I know they look rough, but since T-nuts don’t need to look good, I didn’t do any finish cuts. Now… If I can saw straight.

Thanks for the help my friend!
Tom

P.s. Now I know why you recommened short stubby drill bits.

[david pierce]

Tom,
The finish looks normal for a side endmill cut on steel. Different materials produce different finishes. Steel has a tendency to rip and leave a rougher finish than brass or aluminum. To make the finish a little nicer you can leave a few thousandths for your finish cut and climbcut on the final pass. Also, when I mill anything I always apply oil (cheap motor oil) onto the part and cutter with a cheap paint brush.
david

[tmac1956]

David:

I do that too. I’ve worn out two little brushes on this effort. I’m so happy that it turned out symetrical. I basically used the die and layout scribe lines by my digital caliper. I just eye-balled the cuts and got as close as I could to the scribe lines. I still need to get those digital indiiactors and magnets.

Here’s a question from this project.

I have a little wobble on my Y axis table. If I take the handle off and tighten those star gib screws up, would that do it?

Thanks!!!
Tom

[david pierce]

Tom,
Yes, that is what the adjustment screws are for. Make sure that you do not get them tighter than they need to be in order to tune out the wobble. If they are too tight it will wear out the leadscrew and the dovetails. I think now you can appreciate the advantage that a heavy cast steel machine has over lighter machines. The heavy machine can be pushed a little harder and handle more difficult to machine materials such as steel. As you do this more and more this will start to make even more sense.
david

[arutha]

Well done to you both, I have learnt a lot from the questions and answers that go back and forth between you guys
Paul.

[tmac1956]

All:

I did run across an issue while drill/tapping the holes. The standard charts stated that I needed a 5/16″ Ø drill for the 3/8″ Ø tap (70% thread) … which is what I used. When I set up the tap follower and got past the tapered flutes, I demolished two tap handles just trying to get the thing to do a 1/4″ turn. After some frustration, I decided to try another drill bit that came from ENCO in a set. So, I set everything up for that and the first bit I used was apparently several thousands smaller than the second one. Once I re-drilled the holes, I had no problem at all tapping .

Just for the record… I used Moly Dee as my tapping lubricant, and didn’t do more than a complete turn without backing off to eject the shavings.

Has anyone ever seen this?

Thanks!
Tom

[willofiam]

Tom, well done, I too have learned alot from your posts. David is great help isnt he… William

[david pierce]

Tom,
Always check a drill diameter with your calipers. Just because the drill bit is sitting in a particular hole in a drill index does not mean that it is that size. I have never gotten good resusts with taps that came in tapping sets. They were always junk and produced crummy looking threads. When working with steel it is a good idea to slow the drill rpms down to avoid heating the part as you can work harden the ID of the hole. A common mistake that is made is to spin the drill bit too fast and take light cuts. Just the opposite is required which is slower rpms and a heavy feed.
david

[tmac1956]

David:

Great points.

Thanks!
Tom

[david pierce]

Tom,
Using the eyeball method when centering a part like this with layout die, I would always measure the part, set the calipers to 1/2 of that distance and then scribe two lines from both edges of the part. The center of the part will always be between the two lines produced on the part. If you later get a height gauge and surface plate you can mark the scribed lines in a more precise fashion and the two lines will be more coincident. To line up the spindle center to the scribed line I usually used the pointer tip from the wiggler set. There are many other ways to accomplish the same end result and as long as a correct part is produced the method used is a matter of choice. At some point in time when you can get the machine set up to accurately cut to numbers you will begin to use the layout method less. It will however always have a useful place in machine work.
david

[tmac1956]

Thanks David – I’ll put that in my notebook. I print out and keep everything that you tell me. (old brain).

Later,
Tom

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