What toolholder to cut internal 1.25" x 5 Acme?

Finegrain · Sep 4, 2015

I need to cut 1.25" x 5 TPI Acme internal threads. I generally use lay down threading inserts.

3/4" bars seem to max out at 3/8" IC threading inserts, at least the good ones with swappable anvil for changing helix angle.
Haven't found any 5 TPI Acme 3/8" IC inserts.
1" bar is too big for 1.25" x 5 TPI internal Acme.

Is there another insert type that I can do 1.25" x 5 Acme with?

Thanks, and regards.

Mike

litlerob1 · Sep 4, 2015

I would check out Vardex by Vargus for lay down inserts, you'll probably have to buy a bar though. But you can get #2 Top Notch inserts from any of the big boys, if you can live with that style.

Robert

WILLEO6709 · Sep 4, 2015

thought about a tap?

Finegrain · Sep 4, 2015

I have a Vargus 3/4" bar, but it takes 3/8" laydowns, which there is no 5 TPI Acme for AFAICT.

The only Top Notch Acme 5 TPI's I can see on KM's website are #3 size, and I couldn't find a Top Notch bar that takes #3 size inserts that would fit into a 1.06" bore. Maybe I'm not looking in the right place?

Regards.

Mike

Finegrain · Sep 4, 2015

WILLEO6709 said:
thought about a tap?

Yes, I was quoted $650 for a tandem 1-1/4" x 5 Acme tap :ack2:

.

Regards.

Mike

Philabuster · Sep 4, 2015

Finegrain said:
The only Top Notch Acme 5 TPI's I can see on KM's website are #3 size, and I couldn't find a Top Notch bar that takes #3 size inserts that would fit into a 1.06" bore. Maybe I'm not looking in the right place?

Walk over to the belt sander, grind some clearance on a 1" Top Notch bar and machine the part. Just sayin.

litlerob1 · Sep 4, 2015

Would one of these work it has .5" IC.

ISCAR Cutting Tools - Metal Working Tools - IR/L-ACME : 5902235 - 22IR 5 ACME

R

NodecoMachine · Sep 4, 2015

How deep are you going? We use a solid carbide bar for 1"-5tpi acme from micro100 I think $40-$50 from I remember.

NodecoMachine · Sep 4, 2015

Oh it was accupro. Here is the MSC listing

http://www.mscdirect.com/product/details/57091548?rItem=57091548

Has only 2" reach tho.

BridgeportinD2 · Sep 4, 2015

How deep do you have to go, and in what mat'l?

If not too deep, it wouldn't be too tough to make a bar for the job and get things to come out nice. That insert pocket would be easy to do for whatever size of top notch you want. Grab a piece of 4140/4340, drill, tap, and make the clamp heel relief slot. Heat treat to mid-40s Rc and make the pocket.

I made a dozen parts from AR400 with an odd setup with a tandem tap because:

A) There was no way any bar we had or one that could be bought off the shelf would do the job in AR400 4-1/2" deep with good results

B) The CNC toolroom bedmill (only CNC mill in the shop) was way too light (NMTB 30 taper) to threadmill these things anyway

C) The vertical machines we had that had the grunt to twist that tap didn't have enough Z (before the RA drill showed up) to go through the part, let along give clearance for the tap to come through the bottom of the part

Here's what things looked like at that point:

That's a 20" 1941 Pacemaker. Pulled the compound and made her work like a horizontal. It worked out great, but the cheap tap gave up the ghost going through the last part (thank God it was on the last one). I can't blame that $250 tap for giving up when it did. AR can be some crappy stuff. Used plenty of Moly Dee, too.

Finegrain · Sep 4, 2015

I need to thread ~3" deep. Material is bronze for the parts I have in the queue right now, but I had to do some 2" deep in A36 a couple weeks ago, and that job might repeat.

Regards.

Mike

litlerob1 · Sep 4, 2015

Mike have you tried Toolflo? They have a shit ton of single pointing stuff.

Robert

PixMan · Sep 4, 2015

Vardex makes an internal threading bar that's 3/4" diameter, takes the next-size-up 22IR that's available in 5 pitch Acme, and it has a 1" minimum bore. I have one and used it for a bronze nut that was 2-3/4" long, all I had to do was turn the Ø.771" x 2" long "L1" relief dimension back by another inch.

NVRC075-4 157/009

Insert was a Vardex 4IR-5ACME grade VTX

Other makers sell similar inserts in the more common nomenclature 22IR5ACME. Inserts interchange.

Heavey Metal · Sep 4, 2015

With a 22u insert there is more clearance.

msc has the tandem tap for https://m.mscdirect.com/mobileweb/product_detail?id=04795167&hasRestrictedParts=false

billzweig · Sep 4, 2015

For odd jobs like this (not routine for the shop jobs that one gets once in a blue moon) I grind a cutter to the needed shape out of a piece of carbide (I have a good collection of carbide blade material that was used in cutters for emery cloth) and then silver solder the piece to any convenient scrap piece of steel bar that will fit the tool-post. The whole operation takes about 15 minutes - much less time than trying to search, order and wait. Much less expensive too...

Finegrain · Sep 4, 2015

PixMan said:
Vardex makes an internal threading bar that's 3/4" diameter, takes the next-size-up 22IR that's available in 5 pitch Acme, and it has a 1" minimum bore. I have one and used it for a bronze nut that was 2-3/4" long, all I had to do was turn the Ø.771" x 2" long "L1" relief dimension back by another inch.

NVRC075-4 157/009

Insert was a Vardex 4IR-5ACME grade VTX

Other makers sell similar inserts in the more common nomenclature 22IR5ACME. Inserts interchange.

Yes, I have a 3/4" bar that takes 22IR5ACME, but it has no anvil and the helix angle is only maybe 1*. 1.25" x 5 TPI helix angle is 3*. The 22IR5ACME inserts I am using (two different brand names) have almost no clearance below the cut, and there is definitely interference going on in the last few passes. I have been relieving the inserts just to get by, but would really like to find a solution that is plug-n-play and the right geometry. I see that the Vardex bar has a fixed helix angle of 1.5*, which might be enough to prevent interference.

Regards.

Mike

PixMan · Sep 5, 2015

I used the Vardex "TTGen" software to get the tool selected, though using under 2" depth of thread because I knew the solution would be different if the depth of thread was deeper than that tool's "L1" length. I doubt the software would have given that solution if it didn't have clearance for the given thread diameter and pitch.

It worked for my application in 660 bronze, but fair warning the diameter clearance is tight. With the tool having an "F" dimension (center line to tip of insert) of .494" (x2 for diameter) and a thread minor diameter of Ø1.050, it required being very careful on how much I retracted in X for each pass. Of course being a manual machine I did have "complete control" of that.

BTW, the report generated by the TTGen software shows that the thread has a helix angle of 3.169º and the tool has 3º. I don't know how we came up with different values.

Finegrain · Sep 5, 2015

Thanks Pixman! Looks like a Vardex NVRC075-4 157/009 will do the trick.

Regards.

Mike

Mr.Bronze · Sep 8, 2015

litlerob1 said:
Mike have you tried Toolflo? They have a shit ton of single pointing stuff.

Robert

seconded! Toolflo has been the only source I have for lots of oddball threading tools. Not super cheap, but when they are the only guys around that consistently deliver...

What toolholder to cut internal 1.25" x 5 Acme?

Diamond

Diamond

Diamond

Diamond

Diamond

Diamond

Diamond

Cast Iron

Cast Iron

Hot Rolled

Diamond

Diamond

Diamond

Banned

Stainless

Diamond

Diamond

Diamond

Cast Iron

Similar threads