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View Full Version : Ok, I have done my first "real" machining....



cuemaker
03-30-2005, 11:20 PM
and I am seriously understanding my lack of tools.

What do I consider "real"? Its where the work will actually cost me money to fix if I screw up. Otherwise my time is mostly free and my first 3ft CR rod was free for playing around.

The first thing I did that I consider as "real" was cutting down the plate that slides in my topslide for my QC tool post. I had to take of about a half inch in total to make it fit. I chucked it up in my 3 jaw just like Mr Sparey suggested and took small cuts, but I got there. Came out nice if I may say so.

Well in trying to make some stuff from my CR, I am noticing a serious need for a cut off tool. I have plenty of tooling, just a crappy grinder with wobbley wheels. And no green wheels for carbide. So I am having trouble grinding stuff to what I need plus the grinder takes for ever to remove material. And I must say, I grind like crap.

So I buy me a cut off blade. It cheap, it has a carbide bar cemented to the top (which I cant sharpen yet) and got it from a place that buys and sells surplus tooling.

Well, lo and behold its to big for my tool holder. So i chuck up a used, resharpend many a time 4 flute endmill that a job I worked at 5yrs ago was going to toss since it couldnt be sharpend any more.

I put the cut off blade in a tool holder, put it on my QC post and away cutting i am! I am so pleased with myself.

I have notice that some of you advocate making most of your tooling from blanks. While I would love nothing more than to be able to grind 2 inches down on a HSS blank to make a cut off blade, but I am noticing that it takes forever to accomplish. Is this due to crappy wheels?

i have a cheap half horse grinder. I have used my lathe to spin the wheels, but that doesnt seem to help much except to get my tooling super hot and burn my finger tips.

BillH
03-30-2005, 11:27 PM
Oh, it is essential you learn to grind HSS, just gotta do it.

Sprocket
03-30-2005, 11:36 PM
Or maybe get something like this

http://www.use-enco.com/CGI/INSRIT?PMAKA=397-7406&PMPXNO=945094&PARTPG=INLMK3

that you CAN sharpen, and some other HSS or Cobalt bits that don't require a green stone. I found carbide very frustrating because I really couldn't vary the shape much.

Joel
03-30-2005, 11:50 PM
You need a real parting tool, preferably one that uses a P type blade like Sprocket’s link shows. Look for a parting tool holder that fits your quick change TP, assuming it didn’t come with one.

Like this:
http://www.grizzly.com/products/item.cfm?itemnumber=G5697

cuemaker
03-30-2005, 11:55 PM
That is the tool holder i have joel, and the cut off blade looks like the one from Enco, it just has a carbide blade at the top.

precisionworks
03-31-2005, 12:44 AM
Cue,

Insert-style cutoff blades are available to replace the P-type blade in your QCTP. I got tired of constantly sharpening the Mo-Max Cobalt blade, found an Iscar holder on eBay for $20, been happy ever since.

The only tools I grind are shaper cutters and TIG tungstens. Everything else uses indexable inserts. They are so inexpensive, about 50 cents to $1.50 on eBay.

------------------
Barry Milton

IOWOLF
03-31-2005, 08:15 AM
I might add ...KEEP THAT FRIGGIN WHEEL OFF THE LATHE !

ERBenoit
03-31-2005, 08:35 AM
Cuemaker,

Not to get O/T, about the "taking forever to accomplish" and "grind like crap", in regards to grinding. Grinding is a relatively slow metal removal process. However you can "speed the process" up a bit. Your 1/2 HP bench grinder should be sufficient for grinding of tools. The wheels, well, they could be crap, loaded, or too fine for what you are trying to accomplish. Check the RPM on your bench grinder. Most bench grinders are about 3450 RPM. Set up your bench grinder with two wheels, one coarse and one fine. Mine, IIRC is set up with 60 and 100 or 120 grit wheels. You should consider getting a wheel dresser also, if you do not have one. If you have a lot of metal to remove (ie. rough tool shaping) use the coarse wheel until you get near complete then use the finer wheel for finishing. Dress your wheels when they appear glazed. Glazed wheels are "loaded" and no longer cutting efficiently, causing excessive heat and a decrease in metal removal rate. Loaded wheels are most likely causing you to burn your fingers. It is also burning the temper out of your tooling, significantly shortening it's life. Quench the tool you are sharpening often. Wobbly wheels could be out of balance, wheel bushings worn or lack of wheel stiffeners. With good bushings, wheel stiffeners and a dressing, wheels should run true. Always check (ring test) wheels before mounting them. Support the wheel with your finger in the arbor hole. Lightly tap with a metallic object. Listen, the wheel should have a "ring" to it. If you do not hear the "ring" the wheel may be cracked or structurally defective. DO NOT USE IT. A wheel coming apart at 3450 RPM is tough to dodge.

I noticed the bit about using your lathe to "spin the wheels". I assume you mean grinding wheels. If the intent is to replace a bench grinder, I personally would not do it. Most lathes do not have the RPM to allow a grinding wheel to work as intended. Also, no matter how carefully you protect the ways, and how carefully you clean up after the grinding operation, there will be some grit (swarf) about. You will be grinding away the ways on your lathe. Thus causing wear that many not normally occur.

As far as "I grind like crap", well, that may be true, don't knock yourself, we all did at one time. How much of it you do will detremine how good you get at it. As Bill H put it, learn how to grind your lathe tooling, even if you plan on mostly using inserts. Practice with plain ol' keystock. Don't burn up your HSS and money practicing. Inserts are nice, I use them, but they can be pricey and you learn nothing about how to shape a cutting tool. If you need a unique form, you're probably not going to find an insert, but you can grind it from a HSS blank. The only thing you learn from inserts is how to index to a fresh cutting face.

[This message has been edited by ERBenoit (edited 03-31-2005).]

andy_b
03-31-2005, 01:34 PM
cm,

i am having the EXACT same problem as you. as i get machines running, i realize all the tooling i need to use them. so far i'm doing pretty good, but like you, i need to get a cutoff tool. i have a tool holder that came with the toolpost kit i bought, but in all the boxes of HSS i've picked up at sales lately, i only have one piece of cutoff tooling, and it doesn't fit the toolholder i have. that Enco tool looks like one i may need to order a few pieces of.

as for grinding, i also had the same problem you have. my grinder is an old 6" 1/2hp import thing i got for about $45 20 years ago. it is on its last legs. i ended up getting the Harbor Freight tool grinder a few weeks ago. they were on sale for $119 and even without doing the mods posted here, it seems to work good. it also is HEAVY (maybe 90 or 100 lbs.???). of course, now that i have it, and have picked up a bunch of HSS cutters, i haven't had to use the grinder much because the HSS i found covers most of what i need.

andy b.

jackb
03-31-2005, 01:46 PM
cue & andy,
you guys might want to look into a a basic machine shop extension course through the local college or high school. They usually spend quite a bit of time on how to grind you own tool bits.

Jack

Boomer
03-31-2005, 04:02 PM
I found this site helpful for grinding HSS tool bits..

http://www.sherline.com/grinding.htm

Bruce

PSD KEN
03-31-2005, 04:06 PM
It's like razors, they could give you the lathe, and make $$$ off tooling.
Always a tool to grind, fixture to make, the project is secondary. Figuring how to make a jig, holder, etc is part of the fun.
For sharpening HSS, the Delta 6" variable speed grinder works well, two wheels, course and fine.