Howdy,

I need to make a set of engine stand offs for a Brison 3.2 and another set for a Brison 2.4. Since hardwood dowel is easy to get and work with I was wonderng what diameter of dowel I should use. I am needing to make these stand offs 2 inches and 1 1/4 inches long. I have some 1 1/8 dowel and I wondering if that was too small, or would something larger be better?

TIA for your help!

Never did like attaching anything important into the end grain of wood as you would using dowel.
The strength is not there. Make a friend some standoff for his DA50 test stand use just hole sawed some hardwood (cross grain) that was handy.

I just mounted my Brison 3.2 and needed 3/4" standoff for my plane. I took a piece of very old and hard 1"x8" lumber that I had laying around and cut it the shape of the back-plate then cut out the center essentially making a 'donut'. I drilled 4 holes in the corners and mounted it. It weighs next to nothing and it supports the back plate completely around it's edge. I was going to use dowels but I had the same concern as mikenlapaz with the end grain. I also wasn't happy with just mounting on the four corners with no edge support.

I too needed 2" stand offs for my Brison 2.4 in a P-51. I made them out of hardwood dowels but chickened out and got a metal shop to cut me 4 - pieces of 1" round alum. rod and had 1/4" holes drilled through the middle on a lathe. Cost me $20 and they are much better.

I have been using red oak 1" dowels to mount a ZDZ80RV engine on my Super Decathlon. After over 40 flights there have been no problems. I did epoxy steel washers to the front of the dowels after I cut the correct angle on the dowels for the offset that I needed. 3/4" diameter should be plenty for the 3.2.

Ken

Instead of dowels, I prefer using hardwood stock and a hole saw. You get to choose the grain direction you want, and the hole saw
nicely makes the donuts with a center hole for the bolt.

When you attach this way, I strongly recommend that you use long through bolts to blind nuts in the firewall. Doing so puts
the wood under compression, where it is incredibly strong. If you try bolting the way DA Aluminum standoffs are (one bolt
from the back forward and another from the front back) it won't be as strong and there will be more vibration.

Thanks for all of the replies. I have Red Oak hardwood dowel and was going to simply bore though the dowel to bolt to the blind nuts in the firewall. I didn't think about capping the dowels with a washer, but after seeing it I am going to do that too. Thanks for the pic Ken!

Yes, I do use a hard socket head cap screw all the way through the dowel into a blind nut on the back of the firewall. The redwood makes a very light mount and it will not have a tendency to loosen up with the washer caps. Simple, cheap, easy to make and hard to beat.

Good luck Galen,

Ken

You can also wrap the dowels, or at least near the ends with a good strong string and CA glue it on. Makes for a very strong steup.

just do it right and go to home depot and buy some 1/2 inch aluminum tubing and 8 flat 1/4 inch fender washers and not worry about them splitting uot works great and easy to cut and file

Or go Here [8D]

Roger