AllGoNoShow

Well for christmas I got a brand new Cratfsman die grinder, 6" carbide bits, a router speed controller(from Harbor freight). Well I put all the bits in the die grinder and even on the lowest setting for the speed controller the bits wobble, if you look at the ends it looks like there are two of them ...I tried porting a test head and it just seems hard to control and it wants to follow the casting marks and it seems to jump all over the place. I bought the carbide bits off a place online that I got from a link on this website so I think they are good. I even made an rpm controller from a dimmer switch with directions I have seen on here but the grinder still spins way too fast it seems and it wobbles. Any tips on how to remedy this or how to better control the grinder would be helpful.

AJ_92RS

You have to make sure the bit is set in the absolute center of the chuck. If it’s off the slightest bit (no pun intended ) it will vibrate.

And sometimes you have to find the 'sweet spot' in the RPM of the grinder.

As you well know, there are bearings in the grinder. There's a clearance between them and the shaft of the chuck which goes into the motor.

If the RPM doesn't match the balance of the bit, you'll get a wobble. There's really no way around it. You just have to increase the speed until the bit/grinder spins smooth.

Another problem may be the bits are slightly bent, or not concentric circles. If that’s the case, the grinder’s ‘sweet spot’ and the bit’s ‘sweet spot’ may never match.

One final problem could be the tolerances of the bearing clearance in the grinder. They’re mass produced, so the margin for error isn’t small (i.e. they’re sloppy). Replacing the grinder may help.

I’d follow this order to keep down-time at a minimum...

I’d try increasing the RPMs first to see if you can get the vibration to stop.

If that won’t happen, exchange the grinder.

If that still doesn’t help, then you’ll need to exchange the bits.

EDIT: I just noticed that you're at the 2nd gen site to, aren't you...

Sitting Bull

Also, the cutter must bottom into the chuck. That is, it must reach all the way down before you tighten it. This is especially true for the longer cutters.

I found that the six inch cutters would wobble a tiny bit no matter what speed I ran the grinder at. But once I started cutting it would settle down.

F-BIRD'88

With the speed controller you should be able to
run at any rpm you want.
Check to see if it is the grinder or the bits causing the problem.
Put a 1-4" drill bit in the grinder and try it for vibration.
If there is a lot of vibration, the die grinder is poofed.

The long 6" shaft bits will tend to vibrate if they are a bit off as compared to the shorter 2.5" shaft bits.
Hold the bit hard against something while running the grinder to see if it will true up.
When the bits are new and real sharp they tend to catch, chatter and jump around more.

Are they all bad?

AllGoNoShow

Well I got a different dimmer switch and put it on and it is better and allows me to really slow down the bits, making them a lot more controllable. When I was cleaning up the valve ridge the cutters really didn't jump around at all but when I tried putting them in between the valve guide and the bowl roof it started chattering and jumping around a bit. I will put in a couple hours with these heads hoping to get the cutters slightly dull like you suggest.

F'Bird'88-I've noticed in past posts you seem really knowlegable about porting...if I threw you an email showing you the pics of my porting jobs(both the practice heads and the real things(world s/r heads)) would you be willing to give me some advice on how they look? I've read all the posts and have the Vizard books but I would appreciate some first hand advice.

One more question guys...does anyone know if you can fill in the heat riser passages in the two middle exhaust ports with anything like JB weld? I don't need them and figure maybe there is some power there?

F-BIRD'88

Sure , send me some pics

Or you can get a Yahoo-Photos online account free and
upload them . Then any one can go there and view these pics and see your progress. Just post the yahoo-photos link.

My email is russ_q@hotmail.com

On one set of 305 heads I ported before; I filled the exhaust heat riser passages in the heads with molten cast aluminum. (melted down and used an old cast piston)

AllGoNoShow

Care to describe the process that this involved? What do you heat them up with and how do you pour them in? Does it really help flow at all? I have some cast aluminum pistons laying around I think. Would JB Weld or something like that work or does it get too hot in there?

I will post the pics on my webshots community page in the next few days, it should be interesting to see how well the pics turn out with my crappy camera.

82CamaroZ28

Yeah, i would like to know a little more about this also...I dont have any pistons sitting around or any means to melt them or get then into the passages...

F-BIRD'88

I made up some curved and contoured shaped pieces of sheet metal to block the exhaust EGR passages in the exhaust ports bowl. They have to fit snug over the
hole on the bowl so that the bowl does not get filled up with aluminum when you fill the EGR passage with molten aluminum.

I made a container to hold the aluminum while heating it
and to pour from, from a cast iron plumbing pipe union/adapter with a pipe plug in one end. Makes a little cast cup that can take the heat of a torch without melting.
Break up the old cast aluminum piston and put it in the
cast iron cup and heat it with a o2/acetelene torch.
Need lots of heat. Heat the bowl up so the aluminum
is all melted and smok'en hot. Hotter the better.

Pour the aluminum quickly to fill the egr passage.
You only get one shot at doing it right as the aluminum
solidifies as soon as it hits the cool(er) metal of the cylinder head.
Let the whole thing cool off by itself. then remove the sheet metal shims from the exhaust port bowl and grind
the bowl smooth again.
Note: stuff something into the exhaust guide hole so
nothing gets in there while you pour.

F-BIRD'88

...

AllGoNoShow

I may have to try this...any idea how much of a piston I use for it? I'll try it on the test head first.

And does this provide any significant amount of gain?

F-BIRD'88

At least 1 piston for each.

When i got these heads flow tested I didn;t tell (the shop) which ports to test specifily so I don't know.
Didn't hurt any.

JBweld won't work.

F-BIRD'88

Some thing like this has potential to work.
I haven't tried it to block the egr passage but I did use a very simular product ( different lable) to repair
a hole in a cylinder head that wnt into a water jacket and into a exhaust port. (long story, don't ask) and it worked.
You could jamb a pice of steel in the hole and seal it up
with this stuff.

It actually gets stronger and harder with heat. I allowed
it to fully cure for a week.

http://www.canada-por15.com/por-15-fireseal-2000.htm

There are simular products available sold under differnt brands and names. They are all silica- resin based products. Simular to muffler cement but with metal added.

Pat Hall

iTrader: (31)

Ummmmmm, as far as blocking off the egr passages, I'm surprised nobody has mentioned the low-tech idea of using the tin block off plates you get with a lot of the fel-pro intake gasket sets that are intended exactly for that purpose. The main benefit of blocking off the egr heat riser is keeping your intake manifold cooler, and the little tin plates in those gasket sets should accomplish this just fine.

rustybluebird

Yah, that does work fine if all you want to do is block of the passages
The general idea when a peson spends time to port cylinder heads they are truing to improve port flow. Where the egr passages exit the exhuast port is on the long side/back of the bowl. That hole does not look like it is very helpful in letting the exhaust exit smoothly from the seat to the end of the port.

AllGoNoShow

Guys, where is a good place to get those little rotary stones, like the ones that come in the Standard Abrasives Porting Kit? I like to use them for final metal removal and they are a lot more controllable and the Porting Kit only gives you 2.

F-BIRD'88

Any place that sells tools.
Any place that sells grinding abrasives.
Any place that sells air tools.
Any place that sells welding equipment.

Walmart

Pat Hall

iTrader: (31)

Thanks for the explanation Rusty. Now I see what you guys are getting at!