View Full Version : Last evenings project (pic warning)

07-08-2007, 04:02 PM
In my most recent issue of HSM (Or maybe Machinist Workshop, get them confused) there is an article on building a little air engine out of a 4" piece of 1" round. I didn't build one of those. However in the article the author used a slitting saw comprised of a 3 3/8" trim saw blade. While browsing the tool section at the local HD what jumped right out at me? You betcha!





The blade was something like $14. I made the arbor out of some scrap 1144 I had laying around. The blade has a 15mm center hole and I used a 3/8x24 bolt to secure it. The kerf on the blade is .039 btw and it has 24 teeth. I had to go back, after these pics and reduce the diameter slightly and cut a flat on the shank to use it in the endmill holder shown.

All I have to say is this thing works great. As the pics show I tested it in some cuts over 1" deep and speeds from 100 to 500 rpm. In aluminum at least, 240 rpm seemed to be a sweet spot, at least keep it over 200 for smooth running. I know I could run it a lot faster but I'm not in a big hurry and at lower rpm's it doesn't fling hot bits all over the room! As far as feeds go, crank it, I could turn the handle as fast as I wanted. I don't have a power feed on the Y axis of the machine in use but I would guess about 60ipm at least. All in all, a very useful little gadget.

07-08-2007, 04:12 PM
Thanks for the idea, and the pics.
Nice job!

John Stevenson
07-08-2007, 06:13 PM
Brilliant buy.
Get a blade, grind two teeth off for clearance, make a holder from two big washers and a lump of square welded on and you have a replaceable parting tool like this.


This one is built into a quick change holder but you could just use the square bar in any holder.
This one also has holes drill in to stop it rotating but you can use the gullet of an unused tooth to do the same.

Not seen these small blades here yet.


07-08-2007, 06:33 PM
Sir Sudspump,

As far as I know Makita and Sears Craftsman are the only brands that made a saw with this small (3 3/8") size blade. I have only seen them in 20 and 24 teeth. Most of the other trim saws are either 4 3/8, 4 1/2, and 5 1/2. I thought the 4 3/8 might use the same size arbor but was wrong, its actually a good bit smaller at 3/8" inch. I was wanting to try the 4 3/8 size because you can get it in up to 36 teeth commonly. All of these sizes can be picked up on Ebay for change.

07-08-2007, 06:53 PM
Plenty of saws here. Cheap, too.

07-09-2007, 03:31 AM
Heck of a good idea. I can buy a 3 3/8 36 tooth locally and I think I will pick up one tomorrow.


http://www.canadiantire.ca/browse/product_detail.jsp?PRODUCT%3C%3Eprd_id=84552444329 5404&FOLDER%3C%3Efolder_id=1408474396672841&bmUID=1183965763519

Your Old Dog
07-09-2007, 07:53 AM
Great idea! Looks like an easy answer for aluminum. What might be the smallest R8 collet that would hold it without spinning in the collet?

07-09-2007, 08:17 AM

I'm not sure as I mounted it in a .75 end mill holder. By watching it run I don't get the idea that it is putting any kind of unreasonable load on the machine. However rigidity is always good so I would always go with the largest size possible. Isn't 7/8 the largest R8 collet size?

Your Old Dog
07-09-2007, 08:35 AM
Thanks James,
I think on my setup I only go to 3/4 but not absolutely positive about that. Maybe I'll use it in the other style holder that I have that does go to 3/4". (having a brain fart now or I'd tell you it's correct name! but it's the one type holder with the setscrew in it.)

07-09-2007, 09:08 AM
However rigidity is always good so I would always go with the largest size possible.



07-09-2007, 09:49 AM
You can get the small diameter tipped blades in B&Q not cheap I bought one for fitting in a Rotozip for cutting the bottoms off some kitchen cabinets so as to fit esxteranl feet and didnt wnat to disassemble the lot. If memeory serves right it was quite thin to about 2mm.