What insert to use?

Those endmills work great. I don't know about TPC, but TPG means "triangular positive ground" which means the insert is triangular shaped, has positive rake, and a ground finish. TPU is unground, so the inserts should be cheaper but won't have as good a finish.

I suggest getting TPG-321 inserts. Buy a few of them to get you going, and start looking for them cheap on ebay. It might take a few months of watching, but you should be able to get those for less than a buck apiece.

GWE

T = triangle P = Positive 11 degrees relief G = Ground U = Utility C = Ground with closer tolerances than G

3 = size 2 = thickness 1 = 0.1 mm corner radius 2 = 0.2 mm corner radius

I did not look at which endmill you bought, but if it has only one insert there isn't much benefit from buying the higher tolerance inserts. Even with multiple inserts, the U utility grade is probably good enough unless you are really fussy on the finish.

These inserts are very common and you should be able to find them on Ebay or on sale.

For aluminum you could use ones with more relief. Instead of P in the second place, you might try D,E,F,OR G.

Dan

Rex B wrote:

On Wed, 23 Mar 2005 07:58:34 -0800, Grant Erwin

According to the catalog the ANSI nomenclature is:

T = Triangle

P = 11 degrees relief

G = ground with +/- 0.001 inch tol on the I.C. [outside] dimensions and +/- 0.005 on the thickness.

U = unground with +/- 0.010 on the I.C. and +/- 0.005 on the thickness

C = ground with +/- 0.001 on the I.C. and +/- 0.001 on the thickness.

I have used both TPU and TPG and could not tell any difference.

Last digit in 320,321,322,323 is the nose radius.

0 = 0.004 inch nose radius 1 = 1/64 inch nose radius 2 = 1/32 nose radius 3 = 3/64 nose radius 4 = 1/16 nose radius

I find that the nose radius does make a difference. The bigger nose radius tends to give better finish and longer insert life, but some materials require smaller nose radius to avoid chatter and squeal.

Coated inserts seem to give better finishes for me and lost longer. TiN [gold] is good I have not yet tried the TiC coatings. The Al2O3 coating dosen't work well on aluminium but is great for cast iron.

For home shop and light volume production coated inserts appear to eliminate the need for C2 and C6 grades, and has allowed us to use C6 for everything.

A google search for tpu-322, etc. turns up lots of bargins.

GmcD

Thanks to all that replied, good info. The indexible tool holders I bought for the lathe use the same inserts, so I did good (by accident). I'll go shop at the local surplus tool emporium today.

You're going to use this on a minimill? Which minimill is that? Are we talking 150 Lb Chinese minimill or 850 Lb? It makes a difference.

Jon

FWIW, I bought one of these (R8 TP insert holder) for my old Bridgeport 1J head machine. The machine wouldn't take it. I guess its for sale if someone wants one.

On my Excello (WAY more rigid) I find the high performance inserts are worth the extra bucks. You wouldn't believe how fast you can remove metal with a Sandvick R-390 insert. Same deal with my 10EE, the CNMG inserts with the LF chipbreaker remove way more metal and give more accurate results. By that, I mean the TPG seems to cause more deflection pressure and gives not as repeatable results. Of course, both these inserts are 5X more expensive. You gets what you pays for.

Karl

For mini-mill use see SKU 1093-0835 at

shank 1/2, 9/16, and 5/8 diameter carbide insert end mill set for 25.76. Also available seperately.

Takes TPG/U 22X inserts.

Works well on our Emco mill. ideal for machining steel with scale.

GmcD

Uh, yeah. 150-lb benchtop minimill, of the oriental persuasion.

You mean your BP did not have the power or rigidity to drive it?

The one i got was 1.25". I figured to use it to face things flat. I realize I won't be hogging large chunks of metal with it, but I figure I can shave off .010 per half-width pass.

On Wed, 23 Mar 2005 14:18:47 -0600, the inscrutable Rex B spake:

Which did you buy (and why), Rex? I've been eyeing the info on

and just in case I find my crowbar and break out the wallet some day soon. The HF looks to have the longest Z travel and I can get a lifetime warranty through the local (25 miles away) store, so that looks to be the most solid bet for me.

I have run one like that and a larger 5 incert in my Millport with great results. I would think a Bridgeport in good condition would have the same results. "Karl Townsend" wrote in message news:5Zi0e.2560$ snipped-for-privacy@newsread3.news.pas.earthlink.net...

I bought the Homier version. It was cheapest at $399 plus local tax, no freight since I picked it up locally at one of their traveling tent sales. I actually paid less, but that's another story. R8 Spindle. As far as I've determined the machines are absolutely identical from any vendor save for spindle taper. MicroMark's version has true inch-dials, at $110 more $. I never buy warranties, so that doesn't appeal to me. As for the Z-axis, you can get max travel out of any of them by going to the gas spring from LMS.

Unlike the 7X minilathe, none of them offer different configurations or accessories at the base price.

On Thu, 24 Mar 2005 08:18:11 -0600, the inscrutable Rex B spake:

Don't you have to return the entire machine for warranty work? (Ouch!)

Cool.

Who needs 'em when you can add DROs?

I normally don't, either, but on something which eats gears for lunch, I thought it might be a good deal. $12 for several sets of $38 gears, as necessary?

Got a URL?

The cheap base price is the key.

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I'll fix it myself, and likely upgrade whatever broke

Agreed. I wish MicroMark would offer a DRO coonversion like they did for the minilathe. It had LCDs instead of degreed dials.

Granted, but the diff is $112. That's 3 sets of gears. Besides, LMS sells the gears separately for $5 - $7 each. The complete spare gears set is $30.

I can't find it on

but I have seen it in their printed catalog. It's also referred to on several of the enthusiast sites. Apparently the early models used the gas support, later ones use the spring. You just order the parts for the early ones.

On Thu, 24 Mar 2005 15:26:05 -0600, the inscrutable Rex B spake:

You'd make your own gears, the common replacement part when you forget to lock the head to the gibs?

LMS has DRO kits for "only" an arm and half a leg. (twice the purchase price) but you can find the same imports a lot cheaper on Ebay, etc.

Yeah, you did get a deal on that machine.

Ah!

Oh, _that_ LMS. ;)

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Some people have changed the gear drive to a toothed belt to make the drivetrain more forgiving.

$39.95, improved design

Real quickly I can see spending $200 in upgrades before I make the first chip. Already spent $111 on collets and endmills from Enco.

On Fri, 25 Mar 2005 01:05:50 GMT, the inscrutable Rex spake:

Shoulda talked to Gunner. I hear he has one or two spare collets laying around there.

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