HFT mini lathe mods

[Mikebits]

Any suggestions on a good lathe tool brand. I still use HFT bits which break constantly.

 

[jpanhalt]

If you are using ground bits (i.e., ground by hand) any HSS or cobalt steel from a reputable supplier will work. I don't even consider the brand. J&L/MSC, PTS, Rutland (if still in SOCAL), etc. will have American and European cutter stock.

If you use carbide inserts, get good 3/8" holders - 1/4 IC inserts - (Kennametal, Borite, etc.; there are lots of good brands.) and good inserts. McMaster is not too bad, but I generally wait for sales at JL/MSC or others to stock up. I have a lot of Interstate brand from J&L; they are inexpensive and work fine. I don't really have an opinion on coated inserts for general machining. For threading I tend to go with coated Kennametal. Probably >90% of your work can be done with just a LH and RH cutter, but you do need both.

Don't get too caught up in the different grades of carbide offered. There is a bewildering number available. Remember, they are for production machines making 1000's of the same part. McMaster has a nice, simple description: McMaster-Carr

If you get a general purpose grade for steel, it will work with anything you will be doing. If most of your work will be non-ferrous, then get a non-ferrous grade. It will still cut steel on the few occasions you need it. That's how I get my nicely sorted and organized inserts mixed up. I doubt a hobbyist can tell the difference. The most important things at our level for good finishes are speed, feeds, alloys, and coolant or lack thereof (many aluminum alloys cut great without coolant when using carbide).

John

 

[Mikebits]

I do not know how to grind my own bits, would love to learn, and I do have a grinder. Can you recommend any good book on this subject?

I currently use these HFT garbage bits. - Harbor Freight Tools - Quality Tools at the Lowest Prices

 

[jpanhalt]

I am equally terrible at hand grinding and generally dread it. Part of the trick is to have a stone that is not too hard or too fine, as hard and fine stones will more likely burn your cutters. I prefer a white stone for most HSS final shaping and have a very soft, speckled grey , coarse grit (40 or so) stone for rough shaping. I use a hand-ground cutter when I need a special shape, such as a one-time groove, and my cut-off tool is hand ground. I do have a tool grinder with cupped wheels. One end is the coarse grit stone already mentioned; the other is a diamond wheel for carbides. I can get a couple of sharpenings from an insert, which saves cost.

There are tables that tell you what the various rakes and clearances should be. I generally just use a few degrees of side and back rake plus clearance on the front. There is no side or back rake on the cut-off tool, so it doesn't hog in. It just has clearance on the front and sides with a square nose.

John

 

[Mikebits]

I think bit making is an art. Sort of not shared in books. Like the free masons.

 

[shortbus=]

Hi, being a retired Tool and Die Maker I know a lot more about metal working than I do about electronics

Go to **broken link removed** Check out the South Bend lathe book "How to Run a Lathe" Old school but still the best around. What we used back in high school (1960's) to learn basics.

During my years teaching apprentices the biggest mistake people make in grinding tool bits is using too much angle on the bit.

Cary

 

[12345678901234567890]

Here is my taper attachment I made, it replaces the whole crosslide.


And my latest steam engine (compressed air engine)

 

[BrownOut]

Beautiful work

 

[12345678901234567890]

@Mikebits

It looks like you have the same micromill I use. I suspect you will soon be frustrated by the inaccuracy of the downfeed. Here is how I attached the dial indicator mentioned earlier. You could drill and tap the headstock, but using the tension adjust screw works, and the indicator is easily moved out of position, if you need more than the 1" travel it allows. I made brass stand-off washers to fit into the csk hole on the headstock. That way, the mounting lug is riding between washers and is not pressed directly against the casting.

John

View attachment 34639

John
Good idea with your setup.
=======================

Brownout:
Thankyou
=============

Mikebitz:
NICE vise.

===============

John:

Do you have any excess vibration with that setup?

Because, I had troubles with keeping vibration at a minimum, when endmilling due to the headsock gearhousing being used with the microdownfeed engaged.

So I engage the microfeed and twist it to the left until its tight, then tighten the dial on the lever arm keeping everything tight, then to keep the gearhousing from working in a loose manner, I made this adjustable bracket, to keep the housing tight with the rest of the headstock.



Then all my depths are microfed adjusted through the Z axis lead screw to 1/2 thou. accuracy if needed, using the dial indicator against a magnet at the top. And the dial indicator is on a magnet also, for adjustablility.

 

[jpanhalt]

Your method is certainly more rigid. I hooked mine up after I had just made a counterbore about 0.015 too deep while depending on the fine feed calibrations. So, I wanted something simple and fast.

I keep the quill fairly tight and the fine feed engaged while milling. I have not had problems with it vibrating up. Of course, I always set it from the same direction (push).

John

 

[Mikebits]

Here is my taper attachment I made, it replaces the whole crosslide.
View attachment 34694

And my latest steam engine (compressed air engine)
View attachment 34695

Very nice work. I bow to you sir

 

[12345678901234567890]

Thank you very much..