How big of bench grinder do I need?

danielhv · #1 10-21-2007, 01:45 PM

1/3HP too small? How big of a wheel??

Greg Arehart · #2 10-21-2007, 03:07 PM

I hardly have used a grinder. I suggest you would be better off with a belt sander and/or band saw for fabricating most of the parts necessary. I'm currently finishing up the fuselage & about to order my finish kit.

greg

Stephen Lindberg · #3 10-21-2007, 03:13 PM

I have a 1/2 hp cheapie from Sears that runs my Scotch Brite wheel. I have used a yellow Harbor Freight grinder that was way underpowered - don't get one of those. On the shaft end opposite the Scotch Brite wheel I have a polishing pad that has been real handy for keeping the flush riveting set shiny and polished. The flush sets tend to accumulate smears of aluminum which can mar the skin around future rivets. (You can also use masking tape on the flush set..a better idea, actually. Nonetheless, the polishing pad has been useful.)

As far as my bench grinder goes, I almost never use it (7 inch Dayton, two wheels) to build an RV. Much more useful are the 12 inch disk sander and the 1 inch belt sander. The Delta (imported, of course) 1 inch belt sander also has an integral 6 inch disc sander. That one tool would probably be enough for an RV project, but the power of the 12 incher is nice. Works well on aluminum and steel.

(Yes, I know that some people say you shouldn't mix Al and steel on the same tool, corrosion or Thermite production or some such. I'll take my chances on that one. My machine shop contact thought that the Thermite story (aluminum and steel powder mixing) was pretty far fetched, but according to the internet (!), FWIW, someone has had a brief but memorable flash fire they attributed to homemade Thermite.)

I also impulsively bought another real cheapie Sears bench grinder (on sale, includes useless speed control) to use with a wire wheel. Handy for removing rust from steel. It is low on power but OK for light use.

danielhv · #4 10-21-2007, 03:56 PM

I see... I though everyone was all bench grinders. and scotchbrite wheels.... so just get a bench sander instead???

az_gila · #5 10-21-2007, 04:10 PM

No, get a cheap bench grinder as well... just make sure that it's body is a smaller diameter than the 6 inch ScotchBrite wheel.... makes working on long parts much easier...

After parts are sanded on the sanding wheel/belt, they then need to be polished on the ScotchBrite wheel.... get both...

gil A

mgomez · #6 10-21-2007, 04:36 PM

I got a cheap bench grinder from Sears. 6" wheels, 1/3 HP, 1/2" arbor. I have found nothing on my QB RV-7 (so far) for which this grinder is insufficiently powerful.

In my shop, one side has the gray ScotchBrite wheel (the deburring wheel), the other the brownish ScotchBrite wheel (the one that removes a lot of metal.)

I'm sure people built perfectly good airplanes without these things, but man, I can't imagine doing that. And I agree with Gil's comment...if the part is long, you want the wheels to be larger in diameter than the body of the grinder, so that you can slide the part along the wheel.

Regards,
Martin

jsharkey · #7 10-21-2007, 05:06 PM

I haven't used one. I mount the Scotchbrite wheel horizontally in the chuck of my cheapo Sears pillar drill. A couple of decent files and a good hack saw have taken the place of a band saw and belt sander too.

Ironflight · #8 10-21-2007, 06:15 PM

Just SLIGHTLY bigger than the one your neighbor has....

Seriously, I used my ultra-cheapie Home Depot special with the Scotchbrite wheel all the time during my build. I also used my 4" belt sender/6" wheel sander Combo all the time. Both of them together probably didn't set me back more than $150, which is peanuts compared to the time they save - and quality parts they produce.

Paul

L.Adamson · #9 10-21-2007, 06:36 PM

Quote:

Originally Posted by jsharkey

I haven't used one. I mount the Scotchbrite wheel horizontally in the chuck of my cheapo Sears pillar drill. A couple of decent files and a good hack saw have taken the place of a band saw and belt sander too.

Lot's of filing and hack sawing probably would kill me with a heart attack!

I'm in the sheet metal trade everyday, and certainly wouldn't want to do more work by hand than necessary, when working on the airplane.

The big scotchbrite wheel on the bench grinder, along with a 1" belt sander, and el-cheapo band saw were indispensable, IMO. Another great tool was the 90 degree "air" die grinder with a 2" blue Scotchbrite disk.

I have filed manually numerous times, but only when it's not convenient to use power.

L.Adamson

Rupester · #10 10-21-2007, 08:12 PM

I agree wholeheartedly with Paul and L.Adamson. One of the most indispensable tools in my workshop is a 6" bench grinder (Delta, not expensive) with a 6" Scotchbrite wheel. I can't even count all the hours it's saved me.