Set Screw For Tool Holder

Bamban said:
"Nonmarring Flat Point Socket Set Screw
Alloy Steel, M8 Size, 20mm Length, 1.25mm Pitch"

"I just replaced all of mine with 5/8" length 5/16"-18 stainless 18-8 set screws."


I am curious as which of these tool holders use M8 x 1.25 and which ones use 5/16 x 18
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The two are pretty close if my mental math is correct. But mine (the 5/16-18) are for a four-way toolpost of unknown origin on an old Logan lathe. I would not expect the import toolposts, quick change or otherwise, to have fractional set screws, but I've never owned one.

My brother fixed the A/C in my wife's Sequoia today. In the process two bolts on the evaporator broke so he sent me to a bolt supply house down the street. I'd never been there but I'm glad I did. I got a dozen new black oxide set screws and the replacement bolts and they just asked for $2. I gave them $3 and still felt like I was taking advantage after all the prices I had seen online.
 
Bamban said:
"Nonmarring Flat Point Socket Set Screw
Alloy Steel, M8 Size, 20mm Length, 1.25mm Pitch"

"I just replaced all of mine with 5/8" length 5/16"-18 stainless 18-8 set screws."
Click to expand...

As sloppy as the threads are, you can get 5/16-18 set screws to go into the holes and probably work fine. But technically, there is a slight difference between a M8 x 1.25 and 5/16-18 UNC threads.

EDIT: I don't recommend mixing thread pitches like this combination. It could cause long term problems that maybe harmful to your health.... Using words you don't normally use.
 
Last edited by a moderator:
4gsr,

Thank you. I just want to order the correct replacement screws for the ChiCom oversized AXA tool holders I have coming from All Industrial. M8 x 1.25 it is.

nez
 
Wreck™Wreck said:
There is no "correct", there are only choices that last longer then others and on occasion perform better.
A more useful question would be "What works well in this application"?
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OK, I'll bite. What works well in this application, holding the cutting tools?
 
Socket set screws with a flat point are sometimes difficult to find. It is very easy to set up and face off set screws to remove the cup point they come with. Yeah, they are a little tough to cut, but with a good carbide tool, it's no sweat to make it happen. That's how I did the one's I use on my holders.
 
I strongly advise against stainless set screws. Unless they are hardened the sockets will wear and round out much easier than a good quality alloy steel screw. This is an area, any screw used for holding, that needs adjusting or frequently gets tightened a lot, like on a tool post, needs to be high quality alloy steel. I also put just a dot of copper base anti seize on them every once in a while. When they start to feel lose on the wrench I replace them. The wrenches you use are important as well. Quality wrenches that fit well are worth the extra money. If you use a lot of tools like I do its worth it to accumulate a bunch of tool holders and keep the frequently used tool holders mounted in them. I am selective with the tool holders I buy to minimize the number of holders I need but it really saves time to be able to pull the drawer open and grab the tool you need all adjusted and ready. While Im at it the nuts that come on the import toolholders sometimes need replacement as well.
 
BoltDepot.com is a good source if you need standard fasteners. They can be purchased one or 100.
McMasters has very good selection., and like someone posted above, you can cut them to size. I did this recently.
I use SS fasteners all the time for certain applications and have had no problems. I also use a good metal free Molykote
anti seize lubricant for threads from Dow Corning. Never had a problem, even with auto exhaust bolts.
H-K doesn't seem to make short fasteners, at least not in set screws.
 
EmilioG said:
(snip)I also use a good metal free Molykote
anti seize lubricant for threads from Dow Corning.(snip)
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I thought "whoa", Moly in Molykote stands for Molybdenum. But I chased it down, and sure enough, metal free Molykote, Emilio. Sort of like gelatin free Jello... Anyway, thanks for the tip, though I really don't know why I need it compared to the other products I already have.
 
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