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garyphansen
02-05-2008, 10:18 PM
Could some one post a photo of what a treepanning bit should look like? I need to cut a 6" diameter hole in a steel plate in a lathe and I rather not drill and then bore it to size. Gary P. Hansen

aostling
02-05-2008, 10:25 PM
Looks sort of like the lower jaw of a spawning salmon. http://www.jtsmach.com/jtswebshop/Pr_CuttingTools/D327.asp

Carld
02-05-2008, 10:26 PM
Well, there are a lot ways to make a trepanning tool. The cutter will be ground much like a grooving tool. That is it has a taper look to the top of it and the side clearance has to clear the diameter your cutting and it has to be able to clear the thickness of the work plus some. Do a google for beam hole cutter or trepanning tool and see what comes up.

Alan has it right since he is going to use a lathe. I edited my post to eliminate my incorrect reply.

tattoomike68
02-05-2008, 11:28 PM
http://news.thomasnet.com/images/large/029/29972.jpg

This tool is a face grooving tool for a diameter range but thats the geometry in an exaggerated form.

same idea..

garyphansen
02-06-2008, 11:05 AM
Allen: ,Your link does not work for me. Gary P. Hansen

garyphansen
02-06-2008, 12:27 PM
I looked up trepanning on google but mainly all I found was a bunch of information about people drilling holes in their heads. Sounds like good fun doesn't it! Gary P. Hansen

Jim Caudill
02-06-2008, 01:23 PM
Here are some trepanning tools. The one on the left is a metod of trepanning in a mill or drill press. The other 3 are HSS bit, similar bit in a holder, and an inserted carbide bit holder. Hope this clears things up for you.

http://i72.photobucket.com/albums/i183/Ferrofab/MVC-009S-1.jpg

http://i72.photobucket.com/albums/i183/Ferrofab/MVC-002S-4.jpg

ptjw7uk
02-06-2008, 02:26 PM
Trepanning in the head - a bit difficult to get the head in the lathe!!
LOL
Peter

garyphansen
02-06-2008, 04:33 PM
" a bit difficult to get the head in the lathe!!"


Naw, just cut the head off, people who would drill a hole in their own head were not using their head anyway. Gary P. Hansen

snowman
03-22-2008, 05:45 PM
Hey Jim...

Did you make the trepanning tool for the drill press that is shown? How well does it work?

oldtiffie
03-22-2008, 06:38 PM
The trepanning tool for Machine Shop purposes is essentially a parting or grooving tool that is thrust into a disk or plate to make a groove in a flat face. If done on a lathe the disk/plate spins in the chuck and if on a mill or drill the the disk or plate is static and the cutter spins in/on the spindle. The principle is th same in most/all cases.

The shape of the tool is essentially the same in both cases. It is just a parting or grooving tool with the (usually) left side ground off in the shape of an arc so as to clear the groove as it plunges into it. In each case the tool side clearance must be adequate. It has the same problems as a parting or grooving tool - and must be used in the same way with the same care.

It is essentially a coring cutter - not dissimilar to the coring drills that are used to cut sample cores in concrete or to get Geo-technical cores/samples from rock, ice, earth etc. etc.

The common "hole-saw" is a multi-tooth trepanning tool. It may also be seen as - and sometimes actually is - - a bent hack-saw blade. HSS or TC hole saws are in common use by Plumbers and Electricians. Carpenters use them a lot as well - cutting the core for the hole for a cylinder for a door lock or latch-set is a common use.

I have seen naval gun barrels being made from the solid forged billet this way. The core ("slug") was a solid cylinder.

In all of these cases, the principles, requirements and use are the same as the single point trepanning tool used on a lathe, mill or drill.

GKman
03-22-2008, 08:30 PM
Think -One tooth hole saw with a 100% duty cycle. I made one once and will always smile and whistle a tune while chain drilling a big circle. If I could afford one of those Thin Bits pictured it might be different. Looks like they would only cover a narrow range of diameters so you would need a bunch like hole saws.

jimsehr
03-23-2008, 02:26 AM
You need a different insert holder for different size dia parts. But this shot shows a front view of tool. I used to hand grind trepan tools before inserts were common. Ran thousands of parts on turrets and automatic turrets before CNC. I would draw the size radius that was needed on a piece of paper then go to the bench grinder and eyeball the tool till I had clearance.
One thing no one has pointed out was that you should stop just short of breaking through part or you will break cutting tool as center comes free.
Jim

http://i86.photobucket.com/albums/k106/jims_03/IMG_0016-1.jpg

GKman
03-23-2008, 08:10 AM
You need a different insert holder for different size dia parts. But this shot shows a front view of tool. I used to hand grind trepan tools before inserts were common. Ran thousands of parts on turrets and automatic turrets before CNC. I would draw the size radius that was needed on a piece of paper then go to the bench grinder and eyeball the tool till I had clearance.
One thing no one has pointed out was that you should stop just short of breaking through part or you will break cutting tool as center comes free.
Jim



Jim my hat's off to you. With a properly ground HSS could one cut a 6" dia circle out of 5/8" mild steel?

doctor demo
03-23-2008, 04:01 PM
Jim my hat's off to you. With a properly ground HSS could one cut a 6" dia circle out of 5/8" mild steel?
With a properly ground tool the only limits are the size of your machine and rpm range.
Steve

jimsehr
03-23-2008, 04:14 PM
You can use a hss trepan tool to trepan 6 inch dia on lathe . you need flood
coolant so it can be a mess. When I hand ground the tool I would grind the id side of the tool about .02 lower then the other side and this would cause the chip to curl out and not pack on top of cutting edge and it let the oil get to
the cutting edge. Part shown is tool steel and top two rings were bearing
races and the two smaller rings were for another set of races. Also made many races out of 17/4 ss 10 to 12 dia and 2 or 3 inches thick. Most of the time used carbide tools.
Jim

http://i86.photobucket.com/albums/k106/jims_03/IMG_0018-3.jpg

GKman
03-23-2008, 08:22 PM
Jim,
Absolutely awsome. Maybe I'll try again some day. Thanks for going to the trouble to post the photos.

J Tiers
03-23-2008, 08:40 PM
I have used ground HSS bits to cut deep grooves in parts before. If I had gone a little further they would have been trepanned.

Works well, don't know why one would need anything special.

I HAVE seen a circular gizmo with a single bit that was for trepanning.... If you cut right through, the circular or tubular tool caught the part and prevented it breaking things.