Help with 55 degree threads

[michiganbuck]

Likely already said but the old school would be to set the bit/Insert ti the part with a 55* fish gauge.

Screw Thread Cutting Gauge 55 Degree Wyeth Centering Gauge Measuring Tool 1x 607376819795 | eBay

[trevj]

Hi Trevj. Thanks for the answer. Already done. I went over the setup, once I'd seen the result, and checked everything.

The holder, as I indicated elsewhere, has a flat face on the left of the tool which was presented to the side of the chuck in order to set the parallel to the chuck or 90* to the work as I've done many times before doing 60* threads with the same holder and a 60* insert. Only difference was the insert changed to 55* and the compound to 27*. And before you ask, yes the holder was reset to parallel after the compound was changed. I may be old but not senile. Yet!

My thread gauge has a 55* side to it but the insert tip is so short that the tip will not register in the smallest slot on the gauge so setting the tool to 90* is a guess at best and as far as I can see its ok.

As to grinding my own tools, I've done it in the past before insert tooling was available to me but I purchased these inserts and insert tooling when I came to Canada as I had to renew my tooling so went with what is readily available.

As to the sequence of events, the adapter was supposed to be an ER 25 - 5C adapter but I screwed up the thread on the ER25 end. I remade the 5C-ER25 adapter and decided to reuse the already machined 5C end to make a Myford adapter as it just meant turning the end down and threading to suit. It'll work as is but I'd like to know why it went wrong. Guess I'll have to try again and see if I can fix whatever was wrong.
Twisit

Post a picture of your set-up, a nice top down view.

I have had several apprentices 'go over' their set-ups, and made it just as wrong each time!

As long as you have the angle correct, and the cutter tooth pointed directly at the work, the only other thing I have seen repeatedly, is to not get the half nuts closed.

Not knowing whether you are suffering slippage is another issue, too.

I have a Super 7, had an ML7, and am more than passingly familiar with the Myfords.

To get that Buttress type thread form with a 55 degree cutter, something in your set-up has to be janky as heck!

[thermite]

My thread gauge has a 55* side to it but the insert tip is so short that the tip will not register in the smallest slot on the gauge so setting the tool to 90* is a guess at best and as far as I can see its ok.

Except that it has NOT been "OK".

I was "out of the shop", gave up flying, for looong years whilst growing cataracts as were about to prevent driving.

Brilliant surgeon fixed that so well I have 20/15 with the weird range of being able to read the fine print on a vitamin bottle or a highway sign at night the Hell and gone into the next county. "No spectacles required". At any range.

But I never had it so good before, and few folk have 20/15 with that range, ever.
Surgeon says I have "alien DNA". Go figure all Gweilo look alike to the Hong Kong Chinese and of course we are "Aliens" in THEIR homeland..

EVEN SO.. I keep a diverse collection of optical magnifiers about, have had a dentist's mirror in my kit since the late 1950's to present day, and tiny maglite as well.

If you are going to work in challenging size ranges?

"Fix that" so you CAN see the tiny tip. Or anything else the work requires.

Sounds as if the tool and method isn't going to have enough purchase to provide meangfull guidance?

Vetting the shape of the insert should still be practical by other means. Understanding the relationship to the holder and QCTP might be harder?

"Watchmakers" eye loupes - with the spring steel headband for hands-free, are under ten bucks, American. Haven't been withOUT one - if not several - for more than fifty years.

Truth told? They get used the MOST when I'm woodworking.

Splinters thing!

But "try SOMETHING". Guessing may be "cutting it", just not as good threads!

[ripperj]

Try cutting the thread just using the cross slide, the finish might be not as nice as using the top slide, but the profile should at least be right, and will take too slide angle errors out of the equation


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[michiganbuck]

If not having a fish gauge (but for the life of me I could not understand a lathe hand with not having one) a hack way is possible. You hold a scale parallel to he part being threaded and with your loop look at the tool bit point to see that it is straight to the part. Just bring the bit to just touch the part and looking with a loop should get one square to .002 or so. Going by the compound number only is recipe for scrap parts.

This off side thread has been reported so many times here it seem way too common a mistake, and it is a simple check/understanding that should be included in any threading.

[jariou]

I, for one, would like to see a picture of the tool and insert as set up on the lathe. The "fiasco" in the picture looks like a perfect Buttress thread to me. One such Buttress standard is 10 degrees on one side and 45 on the other side for a total included angle of 55 degrees.

I'm wondering if the OP is not using a Buttress thread insert.

Jacques

[thermite]

I, for one, would like to see a picture of the tool and insert as set up on the lathe. The "fiasco" in the picture looks like a perfect Buttress thread to me. One such Buttress standard is 10 degrees on one side and 45 on the other side for a total included angle of 55 degrees.

I'm wondering if the OP is not using a Buttress thread insert.

Jacques

Share with us, if names mean anything:

How do you spell "F**kin' HILARIOUS"... in one variant or another of French?

Just in case.. we need it.. later.

"Boy Scout" thing? Only "sort of"

Essayons!

[tdmidget]

Really would be nice to have a picture of the set up.

[thermite]

Really would be nice to have a picture of the set up.

Be a lot nicer we each found something more useful to do .. and let the poor, struggling, OP sort it out in peace?

If he ain't got lots of klews by now? He will never.

I'm outta here!

[jariou]

Share with us, if names mean anything:

How do you spell "F**kin' HILARIOUS"... in one variant or another of French?

Just in case.. we need it.. later.

"Boy Scout" thing? Only "sort of"

Essayons!

Thermite, I must admit that I don't understand what it is that you find so hilarious. Yes, I made a mistake, I remembered wrong. It is not 10 and 45, it is 5 and 45. That's the thread on the Deckel drawbar.

If such an honest mistake entertained you that much, your life must be very dull. So, good for you if I put laughter in your day. You must have needed it!

As for the language, yes, I can hold a conversation in French any day of the week although my vocabulary around machining terms is limited in my mother's tongue because I got into this hobby later in my life when I was and still am living in the English language.

Jacques

[thermite]

Thermite, I must admit that I don't understand what it is that you find so hilarious.
Yes, I made a mistake, I remembered wrong. It is not 10 and 45, it is 5 and 45. That's the thread on the Deckel drawbar.

Well don't get yer knot in the knackered.

I didn't KNOW YOU had got it wrong, never met a Deckel in any sort of bar at all. The few I've met (in Milacron's inventory) still had all their clothes on, drawbars modestly out of sight.

I figured you had got it RIGHT, and our poor OP was getting near-perfect threads.. just not the ones he wanted!

So, as cometh to pass? I am the naif!



Now it is actually trois fois comique!

And HE gets to laugh!

Well.. "tough job. But SOMEBODY has to do it!"

If yah cannot laugh - at the LEAST .. yer OWN faux pas?

This mangling of materials game can get seriously dog-robbing dull!

[jariou]

Thermite,

As I said, I did not really understand the intent of your comment. Now I do.

As a side matter however, I just realized, after taking another look at the "fiasco thread, that in fact it could not even be a perfect buttress thread after all. At least not a typical one.

Notice that the more vertical flank is now on the "pushing" side of the thread. A buttress thread would typically have the more vertical flank on the pulling side. So it sort of eliminates the likelihood that the insert used is one intended for buttress threads.

Cheers!

Jacques

[Illinoyance]

I don't understand why Twistit does not provide photos. It would have allowed his problem to be diagnosed with 1 or 2 posts.

[swarfless]

Looks to me like the result of a 60 degree tip in a 90 degree holder. That would give the reverse buttress effect.

[J_R_Thiele]

swarfless

He reports that same holder with 60 degree inserts produces appropriate threads.


Twistit

Examine the insert, pocket, and screw:
Is the screw loose?
Is the screw tight, but jambed by a chip so the insert is loose?
Is there an anvil missing or damaged?

Take the insert out and:
see if it is damaged in any way.
Look for a chip in the insert pocket preventing it from seating properly. Shifting when cutting, but back in place when not
cutting so it looks OK.

[swarfless]

Yes, but to me the OP's info is a bit ambiguous. I took it to mean his 60 degree thread angle tip worked OK but when he changed to 55 degree thread angle tip it didn't. I'm suggesting the 55 degree thread angle tip was was of the wrong species for his holder. If he had a 55 degree thread angle tip for a 90 degree holder in a 60 degree holder the result would be 'leaning' threads, where that latter 90 & 60 degree designations refer to the 'offering up angle' of the holder. I must admit I've lost track of exactly what holder he's using but I still contend that the most likely problem is the right thread angle tip in the wrong basic angle holder or conversely he needs to get a 55 degree thread angle tip for his holder angle. Obviously the latter is the rational way.