Author Topic: Making crush plates? (Read 4814 times)

John G. Park · « **on:** June 22, 2012, 01:00:33 PM »

I've read.about adding these for strength but I can't find anything about the thickness to use for a .35 or so.
Wouldn't a C shaped (or U) piece with the big notch for the engine be stronger?
Also I checked at Home Depot and Lowes and they only have 1/8 x2" so if 3/32 or 1/16 is the thickness, what is a source?
Thanks

Gene O'Keefe · « **Reply #1 on:** June 22, 2012, 01:23:46 PM »

Much easier to puchase them pre-made from Control Line Central or from Brodak.

Douglas Ames · « **Reply #2 on:** June 22, 2012, 02:20:56 PM »

Aluminum or Phenolic, 1/8" thickness is the standard on most plans.

peabody · « **Reply #3 on:** June 22, 2012, 05:13:42 PM »

I believe that the Moons use 3/16", and screw them to the bearers and tap them for the engines....neat stuff...they sell 'em, too!

Brett Buck · « **Reply #4 on:** June 22, 2012, 06:18:12 PM »

Quote from: John G. Park on June 22, 2012, 01:00:33 PM

I've read.about adding these for strength but I can't find anything about the thickness to use for a .35 or so.
Wouldn't a C shaped (or U) piece with the big notch for the engine be stronger?
Also I checked at Home Depot and Lowes and they only have 1/8 x2" so if 3/32 or 1/16 is the thickness, what is a source?
Thanks

I have heard that an aluminum "STOP" sign is something like 3/32 or 2mm 6061T6 aluminum. I'm just sayin...

Brett

bill bischoff · « **Reply #5 on:** June 22, 2012, 06:59:10 PM »

K&S sells 6061 aluminum sheet in 1/16", 3/32" and 1/8". Any place that sells K&S tubing and sheet metal should have it, or at least be able to get it for you. I use 1/8" for engine pads.

peabody · « **Reply #6 on:** June 22, 2012, 07:41:19 PM »

Bob Pitkin offered pre-drilled, laser cut pads that were, indeed "U" shaped...of carbon fiber, I believe....he was a neat guy and I miss him.

Gerald Schamp · « **Reply #7 on:** June 22, 2012, 07:58:10 PM »

Eric Rule at RSM has phenolic plates that he uses in his Lucky Boxes, they are 1/16"x1/2"x2". He does sell them seperately and I just glue two of them together to make 1/8" thick and they work great, and are easy to work with, cost is low as well. Another option.

Will Hinton · « **Reply #8 on:** June 22, 2012, 08:25:10 PM »

Quote from Brett, "I have heard that an aluminum "STOP" sign is something like 3/32 or 2mm 6061T6 aluminum. I'm just sayin..."

Brett

My stooge is an old "detour" sign and is that thick plus a fiberglass coating on the one side. works good, the plane sets on the plate thus avoiding blowing the dust up into the intake. NO, I DIDN'T STEAL IT! It was in the garage when we bought the house. However. . .

Jeff Traxler · « **Reply #9 on:** June 22, 2012, 08:36:32 PM »

Hey Will,Ain't it past your bedtime?

?

LL~Let's go flyin,Jeff-E

don Burke · « **Reply #10 on:** June 23, 2012, 11:17:39 AM »

Quote from: John G. Park on June 22, 2012, 01:00:33 PM

I've read.about adding these for strength but I can't find anything about the thickness to use for a .35 or so.
Wouldn't a C shaped (or U) piece with the big notch for the engine be stronger?
Also I checked at Home Depot and Lowes and they only have 1/8 x2" so if 3/32 or 1/16 is the thickness, what is a source?
Thanks

McMaster-Carr sells all sorts of aluminum stuff. A sample of a material I would use for a "c" plate, click below. It's 6061, not the best, but useful: I prefer 2024 or 7075 but that is VERY hard to find and expensive. When the aerospace companies still had surplus material stores here locally they were a gold mine for that kind of stuff. Gone by the wayside!

http://www.mcmaster.com/#standard-aluminum-sheets/=ij731g

Will Hinton · « **Reply #11 on:** June 23, 2012, 05:07:04 PM »

Quote from: Jeff Traxler on June 22, 2012, 08:36:32 PM

Hey Will,Ain't it past your bedtime?? LL~Let's go flyin,Jeff-E

Hey Jeffie, I ain't got no steenkin bedtime, I work for me and I gave me permission to open up late! Or not at all.

Allan Perret · « **Reply #12 on:** June 23, 2012, 09:12:16 PM »

Get a 12" x 12" phenolic sheet from McMasterCarr. The have 1/16, 3/32, 1/8. Use for engine pads, custom horns, bellcranks..

EddyR · « **Reply #13 on:** June 24, 2012, 05:51:27 AM »

Quote from: Allan Perret on June 23, 2012, 09:12:16 PM

Get a 12" x 12" phenolic sheet from McMasterCarr. The have 1/16, 3/32, 1/8. Use for engine pads, custom horns, bellcranks..

Here is a link to the site
http://www.mcmaster.com/?orderview=new#phenolic/=i45xo8

Larry Cunningham · « **Reply #14 on:** June 24, 2012, 12:36:00 PM »

My source for 1/8" aluminum sheet is old front panels for electronic equipment.. I'm pretty sure you can also purchase some 1/8" aluminum sheet from Small Parts Inc.

Just an opinion, but I question how secure 3/16" aluminum sheet drilled and tapped for engine mount screws actually is. Yet I hear the Texas Universal Engine Mounting Plate works just fine.

I prefer the U-shaped version, although it must be fitted to your particular engine.

L.

"When I read about the evils of drinking, I gave up reading." -Henny Youngman

don Burke · « **Reply #15 on:** June 24, 2012, 05:50:47 PM »

IMO 3/16" alum tapped 4-40 with the engine hole pattern is good for mount plates as long as the bolts that hold the plate to the engine are "close" ( within 1/4") to the edges of the engine bearers. Any farther away and there's the possibility of some bending of the alum, again IMO.

SteveMoon · « **Reply #16 on:** June 25, 2012, 06:51:24 AM »

My brother and I have used the Ultra Hobby 'Moon pads' on too many planes to count
with zero failures. The pads measure 3/16 x 3/8 x 2". We drill through the pads to mount
them to the motor bearers and then drill and tap the pads for the motor being used. The
motor is then mounted directly to the pads. As an added benefit it is then possible to
change motors if necessary by simply drilling and tapping another pair of mounting
pads.

Steve

don Burke · « **Reply #17 on:** June 25, 2012, 11:52:35 AM »

Exactly why I use similar mount plates on my airplanes. I build only racers and we're always coming up with a new "engine of the month". So just a new plate an away we go.

Allan Perret · « **Reply #18 on:** June 26, 2012, 11:30:44 AM »

Quote from: SteveMoon on June 25, 2012, 06:51:24 AM

My brother and I have used the Ultra Hobby 'Moon pads' on too many planes to count
with zero failures. The pads measure 3/16 x 3/8 x 2". We drill through the pads to mount
them to the motor bearers and then drill and tap the pads for the motor being used. The
motor is then mounted directly to the pads. As an added benefit it is then possible to
change motors if necessary by simply drilling and tapping another pair of mounting
pads.

You doing this with 60 size engines ?
What are you using to mount the aluminum pads to the bearers ?

RDJeff · « **Reply #19 on:** June 26, 2012, 02:38:02 PM »

Just to be different, I made some out of HDPE sheet that is 1/8" thick. I had a bunch lying around, and figured why not. It might even help fight vibration problems a little...

SteveMoon · « **Reply #20 on:** June 26, 2012, 03:00:40 PM »

Allan: Yep, all engines. We mount the pads to the bearers with 4-40 bolts
and do the same with the motor.

Steve

Larry Cunningham · « **Reply #21 on:** June 26, 2012, 03:15:48 PM »

Brodak now sells an engine "clamp" mounting system which consists of 1/8" aluminum mounting strips. They can be used in pairs or sets of 4; I prefer the latter since the engine beds against metal instead of the wooden engine mounting beam.

My own New Mexico Universal Engine Mounting plate is bored from the back side to accommodate four counter-sink screws, washers, and nuts to mount to the engine (with thread cement). It is simple, U-shaped, with four common bolt hole positions near the corners to mount the plate on a profile model.

For a full fuselage model, the NMUEMP is identical, with a bit more custom fitting on the U-shape to sit snugly inside the nose.

A disadvantage of the NMUEMP is that a custom one must be made for each motor mounting bolt pattern. With a fine blade in my adjustable speed jigsaw and patience, I "machine" the 6061 aluminum 1/8" sheet easily enough. If the material were not metallic, I would suggest a stiff 1/8" carbon fiber laminated sheet to stand up to the corner mounting method.

L.

"If fifty million people say a foolish thing, it is still a foolish thing." -Anatole France

john e. holliday · « **Reply #22 on:** June 27, 2012, 08:51:29 AM »

On the Brodak clamping system, what keeps the engine from moving for and aft or even side ways if a screw gets loose?

Marvin Denny · « **Reply #23 on:** June 27, 2012, 09:35:35 AM »

Quote from: john e. holliday on June 27, 2012, 08:51:29 AM

On the Brodak clamping system, what keeps the engine from moving for and aft or even side ways if a screw gets loose?

Nothing!!!! Ask me how I know??? (Pathfinder) From now on, My planes all get bolts THROUGH both engine mount holes on through the mount bearers!!!

Bigiron

Gerald Arana · « **Reply #24 on:** June 27, 2012, 09:57:29 AM »

Larry C.
That is the way I WAS mounting my engines too, until I developed a serious vebration problem.

It took me a while but I finally removed the engine (Which is an OS 25 FP) and found that both the bearers had cracked at the rear bolts and I only had the two front bolts holding the engine!

My solution was to grind out the mounts so a cap head 4-40 could be used without countersinking the NEW (stop sign material) [I used to work for the county] alum. pads. Much stronger, IMHO.

Good luck and tight lines............always!

Larry Cunningham · « **Reply #25 on:** June 27, 2012, 10:42:10 AM »

Gerald,

Was that a city or county stop sign? Heheheh. (Maybe a Yield sign would be better tuned?)

Engine mounting plates, like so many things, have their subtleties at times.

Best,

L.

"I'm not dumb, I just have a command of thoroughly useless information." -Calvin

Dick Pacini · « **Reply #26 on:** June 27, 2012, 11:10:10 AM »

Quote from: Marvin Denny on June 27, 2012, 09:35:35 AM

Nothing!!!! Ask me how I know??? (Pathfinder) From now on, My planes all get bolts THROUGH both engine mount holes on through the mount bearers!!!

Bigiron

I don't know if this would prevent loosening, but the manual for my P40 ARF said it was important to snug the hold down screws enough to actually distort the hold down plate on the ends. This would create tension on the bolt that would theoretically keep it from coming loose.

I must admit I didn't use the clamps that way, but rather used them as crush pads because of the general feeling about it from most people here.

Larry Cunningham · « **Reply #27 on:** June 27, 2012, 11:46:32 AM »

I wondered if the clamps suffer any distortion when snugged as tight as they need to be? A hard Al alloy would seem to be in order for the clamps.

Also, it occurs to me that some surface treatment, perhaps shot peening or diagonal scoring, could make the clamp much more effective in holding the motor steady in the absence of bolts through its case mounts.

In the end, your system must hold the engine in the proper position and have the engine case mounts bedded firmly and evenly against a flat hard surface that will spread the load smoothly over a large surface.

I don't see a convenient way to escape some work to produce a good system.

L.

"Everyone has a fair turn to be as great as he pleases." -Jeremy Collier

john e. holliday · « **Reply #28 on:** June 28, 2012, 08:43:26 AM »

If you tighten down the screws enough to distort the hold down plate, won't that undue stress of the hold down screws???