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View Full Version : How do I make thin circumerential grooves?



Lee in Texas
07-12-2007, 09:43 AM
Like an o-ring groove, but really thin. I'm talking .010"-.030"and relatively deep (relative to an o-ring groove). Do I need to fabricate a way to hold a motor tool to my lathe cross slide? Is there a parting tool this thin?

It's for making models of thing like beehive oil filters and air-cooled engine cylinders (non-functional)

http://s18.photobucket.com/albums/b136/TopEndSpeedShop/Misc%20Parts/th_FilcoolatorBeehive.jpg

http://www.pw.utc.com/pw/StaticFiles/Pratt%20&%20Whitney/About/History/Assets/Images/r4360.jpg

Evan
07-12-2007, 09:50 AM
Not a good plan to link directly to a file like that, especially when it is 1800 pixels wide.

[edit] That's better. :)

Just regrind a cutoff blade.

TGTool
07-12-2007, 09:52 AM
Lee,

There was an article in HSM or Machinist Workshop, within the last year or so, on using a slitting saw to make very thin grooves like that. It can be mounted on a small spindle and motorized to spread the cutting action over all the available teeth. That would give you considerable depth of cut, but if you need grooves on a long part you might need to make a special arbor, supported on both ends to get clearance.

Swarf&Sparks
07-12-2007, 09:53 AM
"thin" and "deep" require quantifying, but here goes.....
I've used (broken or worn) donkey saw blades as parting tools.
Also used ordinary hacksaw blades on smaller jobs such as you describe.
The vacu-video method (AKA, suck it and see)

Rif
07-12-2007, 10:32 AM
I have a couple of 1/4" HSS lathe tool bits that I have ground down to make narrow slits. Last week I used one, in my mini-mill, to make a slit for the valve in a carburetor shaft. Evan's suggestion of re-grinding a cutoff blade would work the same, as well and would be much faster to grind. I only used 1/4" HSS because I only have 1 cutoff blade; but, I have plenty of HSS tool bits.

Brian

Rusty Marlin
07-12-2007, 11:23 AM
Funny you should ask this today.

Just yesterday I was grousing to the machinist here at work about hand grinding .025" grooving tools and how I'm having trouble keeping the sides parrel; without any hesitation he said, "Why don't you use an old hacksaw blade?" with that fatherly look on his face that adds "KIDS!" to the end of the question.
I hope he isn't planning on retiring anytime soon, he's full of great tips.

ahidley
07-12-2007, 11:57 AM
Get a $3 carbide tipped circular saw blade and cut it up into approx 8 parting tools about 1"high x 4"long x the thickness. grind the carbide down to the desired width. If your cleaver you'll be able to mount it in your parting tool holder.

speedsport
07-12-2007, 02:03 PM
do you mean like "Beaver Cleaver"?

Scishopguy
07-12-2007, 05:54 PM
This brings up a question someone asked a while back, "What would I use a surface grinder for?" Over the years that I worked in Oceanography shop at FSU, I had to make tools to turn various O ring grooves in pressure case end bells and a variety of bulkhead penetrations. I found that I could grind a parting tool with the proper relief on the end of a high speed tool bit of any size. Some of the larger ones took a couple of hours to grind but, concidering the use I have gotten from them over the 26 years in that position it is not a lot of time wasted. The same tools came in handy over and over. The handiest ones I found to be .o62" and ,030" thick. The smallest one I made was .015" and was only used occasionally. The most rugged one was ground onto a 5/8" cobalt bit and was .100" thick. I used it to bore 8" diameter rounds out of a bunch of 1/2" thick stainless plates that became instrument hangers. Couldn't have done it without the good old surface grinder. Grooving tools and cutoff tools are some of the handiest tools in your collection of bits. Tool making and design is one of the most enjoyable parts of the machinist trade. Go out there and keep doing what you do, solve those tooling problems. ;)

GKman
07-13-2007, 07:32 AM
circumerential?

Aren't you supposed to get a Rabbi to do it? ;)

DR
07-13-2007, 08:24 AM
Like an o-ring groove, but really thin. I'm talking .010"-.030"and relatively deep (relative to an o-ring groove).


You can buy tools to do this.

"relatively deep" does need some definition though. Two times depth relative to width? Three times? Four times or more?

Thinbit cutters are available in .004" to .150" widths for up to 2-1/2 to three times that in depth.

I've used Thinbit for years. You buy a holder, then buy individual bits as needed. The bits are properly ground with the correct reliefs, etc. Much easier than fooling around with mounting saw blade type setups.

http://www.kaisertool.com/2004Catalog/Index.htm

oldtiffie
07-13-2007, 08:46 AM
Deleted/erased-out

Evan
07-13-2007, 09:04 AM
I was going to post the same tip as ahidley about chopping up a saw blade but he beat me to it yesterday. I recently bought a new Black and Decker circular saw and it came with a super thin kerf carbide blade that began spitting off teeth right away. I took the blade off yesterday and hacked it into some cutoff blades with my mini chop saw. I use one of the new ultra thin ceramic cutoff wheels in the chop saw and it whistled through the saw blade like it was a dry biscuit.

It shouldn't take much imagination to figure out a way to hold the pieces to use as parting tools. A hand held diamond hone will tune up the carbide teeth to the right edge shape.

http://vts.bc.ca/pics2/chopsaw.jpg

ahidley
07-13-2007, 10:39 AM
Evan has it exactly. Hopefully this weekend I'll be able to take a pic and show my set up and holder.. It works great and mounts in a 1/2 bit holder.
The circular saw blades you can cut EASILY with a band saw or if in a bind a hack saw. I then take the whole stack, last time about 15 and clamped them all in the mill vise and milled them to size, i.e. 1" and they fit in the parting tool holder that I made for them. !! pics this weeeknd.

Lee in Texas
07-13-2007, 08:14 PM
You can buy tools to do this.

"relatively deep" does need some definition though. Two times depth relative to width? Three times? Four times or more?

Thinbit cutters are available in .004" to .150" widths for up to 2-1/2 to three times that in depth.

I've used Thinbit for years. You buy a holder, then buy individual bits as needed. The bits are properly ground with the correct reliefs, etc. Much easier than fooling around with mounting saw blade type setups.

http://www.kaisertool.com/2004Catalog/Index.htm

Wow. That sounds like the least amount of trouble.

Thanks.

ahidley
07-14-2007, 12:29 AM
This is how I cut the circular blade
http://i194.photobucket.com/albums/z80/ahidley/5.jpg
Then I stacked 2 blades worth about 12 parting tools in the ruff in th evise to mill them to the correct height
http://i194.photobucket.com/albums/z80/ahidley/1.jpg
These are a few odd parting tools. left is a thread cutter -middle is a .030 tool used for small e-clips -right is .040 and was used to cut ring grooves in a few 1 inch diameter pistons
http://i194.photobucket.com/albums/z80/ahidley/2.jpg
Rear of the parting tool holder
http://i194.photobucket.com/albums/z80/ahidley/3.jpg
Front of the parting tool holder.
http://i194.photobucket.com/albums/z80/ahidley/4.jpg