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Getting small internal threading bars in a hurry

implmex

Titanium
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Good morning All:
I had to grind a single point bar for an M2 x 0.4 internal thread that needs to be single pointed to keep it as concentric to other features as I can.
I know you can sometimes buy stuff like this if you're willing to wait for it, but sometimes I'm not or I need something weird that I can't get.
So this bar is 0.058" across the tip (it'll go into an 0.058" hole).
DSCN5600.JPG
It took a long time to make because it's so small and I can't see well enough anymore even with a 10X magnifier to be sure I got the geometry right, so I grind a bit, shadowgraph it, grind a bit more, scope it, etc etc.
Each time it needs to be picked up on the grinder again...a royal and time wasting PITA.

Almost 3 hours to grind this bar...that's a pricey bar but I need it this week and I got it today (nutso customer deadline...the purchaser forgot to include the part this tool was made for, in the order...now there's a crisis)

My question to all of you...if you can't buy one from the store in a reasonable amount of time, what do you do?
Turn down the job?
Bodge something together like I've done?
Make the customer wait?
Pressure a vendor to drop everything and make you a special?

I look at CNC cutter grinders popping out cutters like pancakes and I am green with envy and want one so I can do it too.
But under almost every circumstance, it's a stupid idea for a prototype shop to invest in something like this.

My way still kinda works, but it depends on me...I doubt you could hire this capability anymore, and most shops don't have the gear anyway.

So what do you guys do?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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implmex

Titanium
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Hi SeikiCorp:
Thanks for taking the trouble to point me to those...I appreciate it!
Yeah, I looked at them.
They would have done it in this instance...I just can't get them quickly enough for this job.

But ultimately, I am talking about the general case...you need something, you can't buy it for whatever reason, and most shops can't make it for themselves anymore.
What do you do then?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
My favorite internal threading tools are the type made by Bokum. They are spiral form ground for 60 degree threads and can be sharpened by grinding only the top surface quite a few times before they are done. I started buying them around 1980 or so, when Enco sold me some German copies made by Komet to go with my Swiss Multifix AFI threading holder. I bought several different sizes to give myself a good range of possible thread diameters. Komet made them in 55 degree also. Bokum is still in business and does specials, but may not make tools for holes smaller than .062". There is probably still a German maker of these tools. I also am very fond of Bokum boring tools.


So, getting back to the original question. My answer would be to select a tap close to the desired thread and grind away all but one vee to use for single point threading. That way the actual cutting edge will already have the correct form and you just need to grind away the portion that you do not want.

Larry
 

FamilyTradition

Aluminum
Joined
Feb 24, 2018
Location
Greenfield, Mass
Bodge something together like I've done?
I certainly wouldn't call that a "bodge". Sometimes you gotta do what you gotta do to get the job done, and that looks like a nice little threading tool.

Sometimes the only one you can depend on to get the job done - NOW - is yourself. I have been there and done that many a time.

I worked in a shop where we did things like this all the time to get the parts out on time, or fix parts that were non-conforming.

Some folks would say "Lack of planning on your part does not constitute an emergency on my part", but I always like to tackle challenges and circumstances such as this, long as I am fairly compensated for those efforts.
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
I didn't know there was a 55 degree Metric thread. What is it used for?
JH

From the above, "BSP (British Standard Pipe) threads, using the Whitworth thread form, have been adopted as the ISO standard for pipe threads..."

"Metric" (ISO) pipe threads are the old British standard that uses the Whitworth 55 degree form. That is why my German lathe threading tools come with both 60 and 55 degree cutters.

Larry
 

jackal

Titanium
Joined
May 4, 2006
Location
northwest ARK
When a specialty tool is needed for a part, and the customer doesn't provide it, you have to do whatever.
Looks like you made a great tool
I'm not sure how many parts you have to get out of it
I would do what I could, and give that to the customer ( if they were supposed to be provide tooling).
Sounds like you handled it well.
But, you don't won't to do this every time, and you already know that.😉

Great job on your part.
 
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TGTool

Titanium
Joined
Sep 22, 2006
Location
Stillwater, Oklahoma
I don't think there could be a standard answer to "what to do." It would depend on how you want to juggle the factors of customer satisfaction, reputation, job profit and probably others. One might just say "sorry" to some customers you don't care if you see again, but bite the bullet and just hope to break even for others if it's been a good relationship you believe has future potential..
 

Joe Henderson

Aluminum
Joined
May 21, 2006
Location
Blooming Grove, Texas
There's no easy answer but I would charge the customer accordingly. That Bokum thread tool is interesting. I have a little tool like that marked Comet that I've used on a couple of occasions in small hole threading.
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
There's no easy answer but I would charge the customer accordingly. That Bokum thread tool is interesting. I have a little tool like that marked Comet that I've used on a couple of occasions in small hole threading.
I see their tools marked both Komet (German spelling) and Comet. They make dental burs, which show up most often on German eBay, in addition to larger industrial cutting tools.

Larry
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
If it's a good customer you did well. Can't go to that kind of trouble for everybody though or you'd shortly be in the poorhouse. I know you didn't get much of a chance to plan for this job what with the last minute addition to the order, but that's what estimates are supposed to avoid. If a customer did this to me regularly and didn't want to cover the extra costs I would in future make them wait for an ordered tool - and you're damn straight they'd better be paying for that tool or I wouldn't be doing many more last second emergency jobs for them. That's part of a good relationship between a vendor shop and a purchasing agent. They need to be willing to work with you on the added cost when something like this comes up if they want your help to pull their ass out of the wringer. And last second emergencies are not known for being cheap... This is why scheduled maintenance shutdowns are a thing.
 

implmex

Titanium
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Hi again All:
For those who posted comments about taking a hosing by making a custom cutter...be reassured, I definitely charge for it.
Normally, I'd never expose the customer to this cost, I'd just buy the cutter unless it's a special I can't get...the circumstances dictated my decision.

BTW, I did not make the other parts for this order, so I was unaware until I got the email.
Then I fucked up my ankle and was off for a bit, adding to the delay.

But I ran the parts this morning and the tool performed like a champ.
All is well...now to make the mating parts.

They'll be much easier...no single pointed M2 internal thread.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 

James H Clark

Stainless
Joined
May 11, 2011
Location
southern in.

From the above, "BSP (British Standard Pipe) threads, using the Whitworth thread form, have been adopted as the ISO standard for pipe threads..."

"Metric" (ISO) pipe threads are the old British standard that uses the Whitworth 55 degree form. That is why my German lathe threading tools come with both 60 and 55 degree cutters.

Larry
Oh yeah, I ran into that a couple of times on British bike pipe threads. Gonna have to start taking something for memory improvement. Sorry bout this. Thanks for the help.
JH
 

old_dave

Hot Rolled
Joined
Apr 15, 2002
Location
Central Mother Lode, California
I see their tools marked both Komet (German spelling) and Comet. They make dental burs, which show up most often on German eBay, in addition to larger industrial cutting tools.

Larry
At some point in recent years Komet became part of the Ceratizit Group, who continues to sell cutting tools with the Komet name. Unfortunately though it looks like the threading bits for the Multi-Fix external threading holders have been discontinued.

David
 

50BMG DUDE

Aluminum
Joined
Jun 17, 2013
Location
Bonners Ferry
I've done the grind down a tap into a single point tool trick, and it has saved my butski. I have one of the micro 100 or PH Horn bar holders that work great for this.

On a side note, you probably HAVE a CNC tool grinder in your shop Marcus. Go watch the Youtube video on AB tools shop tour. (Jon Saunders @ NYCNC IIRC). They are using old Moon lander VF-1's as tool changing T&C grinders with 4th axis. Probably roughing out stuff on the ones in the video if I remember. I have tried this once for a special form cutter and it worked out pretty well. I prefer to order my customs, and not get carbide grit in my machines, but I used a baking pan under the tool with some shop rags and didn't blast the coolant. ya do what ya gotta do.:)
 

implmex

Titanium
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Hi 50BMG DUDE:
Yeah, I' saw that video once upon a time years ago.
Thanks for the reminder.
I recall thinking..."what a brilliant idea!"

Then I bought a wire EDM with a rotary axis.

Now I can make some pretty crazy cutters if I need to...BUT:
It's a right royal pain in the ass to set it all up for one simple threading cutter so I went back to grinding them on the Deckel SO and the little home made cutter grinder I built for myself back when I had more time than money.
That was forty years ago...how times have changed.

Back then you had to know how to make form cutters if you were going to be a moldmaker, so I learned the skill along with just about every other toolmaker of my generation.
What I want now is a fantasy...walk up to the machine, program for 2 minutes from a canned menu, load the blank, push the green button, and PRESTO...a beautiful shiny cutter, dead nuts accurate, for almost no effort.

When I can force myself, I can still make a respectable tool...but almost no other shops can do it...they no longer have the gear or the crusty old fart who knows how to work it.
So it's a stumbling block for pretty much anyone who wants to get into the sort of work that I do.
I know of a few guys who went back to "old school"...eKretz has a Monoset (I'm still jealous) so does TKassoc (I'm just as envious), but that's not the norm these days.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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