Die Grinder Cutters/Bits ??

My cutters/bits are too short to get to the back of my ports and too work deep in the bowls. Can someone please tell me where to find bits with longer shafts or an extension device to make the cutters I have work better for me?

You don't want longer bits - it will cause problems with the bearings in your grinder. You need a shaft type grinder. The handle on the shaft is about 3/4" diameter and it allows you to go deeper into the port.
Longer shafts will just spin out of balance and break.

Originally Posted by PaulS1950

You don't want longer bits - it will cause problems with the bearings in your grinder. You need a shaft type grinder. The handle on the shaft is about 3/4" diameter and it allows you to go deeper into the port.
Longer shafts will just spin out of balance and break.

That makes a lot of sense there Paul. I found a pencil style grinder that will take my 1/8 bits. I'll give that a try.

Just t be clear for others reading this, I'm using an air driven die grinder and the pencil grinder I'm going to get is also air driven. I think I will use my dremel tool (electric) once I start polishing, but air driven for the cutting.

circofile.com (for the burrs)
MSC or other tool/machinery suppliers (for the long cartridge roll mandrels).

I've been porting heads/intakes for about 7 years. This is what I've found to be the most critical.

1. Speed control. You have this via regulating air pressure. If you use electric grinders (Makita GEO600), a variac is necessary.

2. Correct length and shape burrs.

6" shank and SE (egg) and SC (cylinder w/rounded end) burrs work great on heads and most intake work. A 8" shank is sometimes handy when you want to get deep into the runners of a Vic Jr or Super Vic. You can also get 6", and 12" cartridge roll mandrels. This will allow you to get into almost all areas for the final sand roll work.

Good luck,
Gerald

Be careful on the long shanks. I had one go to instant 90 position when I accidentily hit the full on button without being against any metal. Did end up with a very friendly length burr in the end that I really like.

Those long shank burrs are also hard on bearings. I use the slender cable and hand grip grinders and have no problems using the standard length burrs.

Have to chime in. All the pros use long shanks, However they buy the quality burs. They have carbide heads and hardend steel shanks that take ALOT of imbalance to break.
Good supplier? SGS Tool Company - A Leading Manufacturer of Precision, Solid Carbide Cutting Tools.

That said its important to have a good quality grinder and collet to ensure very little runout at the end of the cutter.
As far as long shanks being hard on the bearings, maybe on the cheap grinders, but on High quality grinders ( ie milwaukee,Makita or Ingersoll) , electric or air, you wont have an issue.
My 2­­­­c

I will be porting a set of 289 heads shortly! Have been away from this stuff for many years and trying to get back into it.Anyway I have purchased a geo600 makita die grinder and a porting kit is on the way. In the earlier posting it stated I need a "variac".Is that like a reostat of sorts to slow the speed of the grinder down? If so where do I find that? Thanks for the help!

Originally Posted by 71hotrodpinto

Have to chime in. All the pros use long shanks, However they buy the quality burs. They have carbide heads and hardend steel shanks that take ALOT of imbalance to break.
Good supplier? SGS Tool Company - A Leading Manufacturer of Precision, Solid Carbide Cutting Tools.

That said its important to have a good quality grinder and collet to ensure very little runout at the end of the cutter.
As far as long shanks being hard on the bearings, maybe on the cheap grinders, but on High quality grinders ( ie milwaukee,Makita or Ingersoll) , electric or air, you wont have an issue.
My 2****c

I agree. Get quality carbide cutters. I have used leather gloves holding the long shanks for better control. you can't do it too long though. I have found wax on the carbide helps keep it clean. An old candle works.