Rough Threads Single Point Threading

[benmychree]

Modified suspension auto parts? Hope that you have good products/liability insurance --- When I had mu shop downtown, this would have been a job that I would turn away.

 

[Sailplane Driver]

It's for a good friend and I'm not a shop. He's already broken several. We're trying some different material to see if these will hold up better. Also, this is not a daily driver, it's primarily for autocross which is as safe a motorsport that there is.

 

[woodchucker]

not sure I understand, the hss should only require one grind and can be used toward or away. Just flip it over.
Also make sure you use oil. I do not thread dry, never will, you are cutting too much metal and are looking for a smooth finish for each pass.

 

[Sailplane Driver]

Conclusion: It's the insert. Here is a nice clean thread (relatively except for a couple with a partial half-nut engagement) on 12L14. I used HSS and ran away from the headstock. I overshot the PD but this was only a test. I need to refine the infeed for the HSS tool.

 

[benmychree]

It's for a good friend and I'm not a shop. He's already broken several. We're trying some different material to see if these will hold up better. Also, this is not a daily driver, it's primarily for autocross which is as safe a motorsport that there is.

The legal exposure exists regardless of whether you are a "downtown" shop or not and friendship extends only just so far in the event of a catastrophic accident, especially with 3rd parties involved. I may have missed a few dollars here and there, but I never had a claim or lawsuit in my 35 years in business.

 

[Sailplane Driver]

I know a fair about professional liability. I was a professional engineer before I retired and carried a large amount of professional liability insurance. I also worked as an expert witness in legal cases, several for professional liability. Fortunately, I am not a professional machinist but a hobbyist. I am not taking money for this work. There is a world of difference in liability. Additionally, any can sue anybody at any time for anything regardless of validity. Deep pockets are what are named in lawsuits. I'm not too worried or I wouldn't do the work.

Anyway, this is a machining forum. Let's not get off subject into liability.

 

[woodchucker]

I don't know, to me the 2 threads to the left look boogered.
Same problem?

 

[davidpbest]

Conclusion: It's the insert.

Another example of why I try to discourage purchase of inserts on eBay unless you have a way of verifying authenticity. Full packs especially should raise a red flag. Those "Mitsubishi MMT11ER AG60" you mentioned you purchased on eBay are not made by Mitsubishi as best I can tell. According to Mitsubishi published information, they do not make an "11" sized (1/4" I.C.) AG60 insert for external threading.

Glad you got your threading accomplished.

 

[rwm]

I think you hit on the real problem here "for a Porsche 944."
But seriously, this was an informative read and I will try to avoid knock off inserts. It's hard on eBay.

 

[Firstram]

The legal exposure exists regardless of whether you are a "downtown" shop or not and friendship extends only just so far in the event of a catastrophic accident, especially with 3rd parties involved. I may have missed a few dollars here and there, but I never had a claim or lawsuit in my 35 years in business.

I worked for Dad in his job shop in the early 90's, we refused any auto work that came by. The only thing we would do is trailer hitches on commercial vehicles. They had the budget to over build everything we touched and we never had a problem. I wouldn't even consider doing it these days.

Being a race team member might be different.