extreme frustration with Shinn brakes

[N74DV]

Re: extreme frustration with Shinn brakes

update

we finally got back the shoes from Skybound (4th time) and yet again they were not the proper size. Could not even fit the the wheels on.

So we drilled out the rivets in the clips on one end of each shoe, welded the holes shot, re-drilled the holes for repositioned clips, reinstalled the clips with countersink AN screws and metal lock nuts instead of rivets and finally after 5 months of having no brakes we can officially say the plane is ready to take to the airport and put the wings on.

[Ragwing nut]

Re: extreme frustration with Shinn brakes

What really sucks about this is that they owe me 6 ship sets of shoes. I sent nearly 30 shoes to re-line and I was suppose to get half of them back. that was over a year ago.

[bashibazouk]

Re: extreme frustration with Shinn brakes

For what it's worth, this is what I came up with for my latest re-lining:

McMaster-Carr's aviation section carries 1" X 3/16" lining material (part #6175K111) in up to 30ft strips (There is no 1/8" listed). They charge $2.53 a foot. It looks just like the stuff I got from Skybound, only 1/16" thicker. I fastened it to the drum (not going to say how I did that-- refer to Rob Lees' handy guide). The I chucked it up in my lathe with a simple adapter for the bearing race:



[Edit]

I used the medium-speed direct drive setting on my old 9" lathe; that equates to approximately 750 rpm at the spindle. My cutting tool is a Harbor Freight special with a carbide insert. The brake lining material is really soft stuff. It's sort of like machining hard cheese. I don't think the shape of the tool matters too much-- this is just what I use for aluminum. It just needs to be sharp!

[End of Edit]

I had already completely disassembled the shoe mounting plate and reassembled it on the bench, complete with the springs to test the fit in the drum. It turned out that once I had everything put back together and tested the brakes, things seated and I had a little more slop than I thought I would. Next time I'll leave it a little tighter-- and the thing probably won't turn at all!!

Not sure if this is helpful to anyone, but I thought at least the alternate source for shoe material might come in handy. Your mileage might vary, I suppose. I'd be tempted to try the semi-metallic stuff, but my shoes are already paper-thin. Maybe when I replace those. I've got a home-made slip roller to duplicate the curve... Need some rivets for the brackets.

Josh

[Hank Jarrett]

Re: extreme frustration with Shinn brakes

Might be helpful for others wanting to try this if you remember the RPM you turned the wheel and the type and angle of the edge on your cutting tool. You know, the stuff a machinist would want to know so he gets a smooth cut. We are going to have this kind of "make it from scratch" come up more and more as our babies age (hopefully gracefully).
Hank

[bashibazouk]

Re: extreme frustration with Shinn brakes

Edited previous post. Good thought, though I will say that "machining" the brake material is pretty easy. You could probably put a butter knife in the tool rest with good results.

I think it's good to know you can use thicker stuff and make it work-- in fact you can tailor it to your specific shoe plate. Also important, since there seems to be so much variation in the shoes.

[Larry Lyons]

Re: extreme frustration with Shinn brakes

For what it's worth, this is what I came up with for my latest re-lining:

McMaster-Carr's aviation section carries 1" X 3/16" lining material (part #6175K111) in up to 30ft strips (There is no 1/8" listed). They charge $2.53 a foot. It looks just like the stuff I got from Skybound, only 1/16" thicker. I fastened it to the drum (not going to say how I did that-- refer to Rob Lees' handy guide). The I chucked it up in my lathe with a simple adapter for the bearing race:

Josh

Josh I just looked at McMaster-Carr and see that you could have got the lining in a sheet in 1/8" thickness. Did you look at this and if you did what was your reasoning for not getting it? I do not need any right now but am curious for future reference.
Larry

[bashibazouk]

Re: extreme frustration with Shinn brakes

Josh I just looked at McMaster-Carr and see that you could have got the lining in a sheet in 1/8" thickness. Did you look at this and if you did what was your reasoning for not getting it? I do not need any right now but am curious for future reference.
Larry

They've got the 15"X15" and 30"X30" sheets in 1/8" thickness, but the 1" wide strips start at 3/16". I just wanted to get a length of the stuff vice cutting short strips and piecing them together.

[DanBrown]

Re: extreme frustration with Shinn brakes

They are handy for a short run-up under 1500 RPM , :

Yes, mine will hold to about 1400 rpm on pavement, and 1600 rpm on grass. A little better heading into a fair wind. So I usually do my run-up in takeoff position creeping forward with the brakes, and then release for takeoff. They're also somewhat useful to help turning away from the wind when taxiing and for a little bit of extra safety when propping.

[VictorBravo]

Re: extreme frustration with Shinn brakes

I can personally vouch for the fact that when set up and adjusted correctly, the Shinn brakes will hold an 85HP engine on pavement at full throttle with the standard 6.00 x 6 tires, and better than 3/4 throttle with larger tires.

A large number of T-crafts probably do not have their brakes in good enough shape to accomplish this. A lot of people don't ever adjust those little nut widgets that are there for the purpose of adjusting brake tension. A lot of people probably have dirt, varnish or grease on their brake parts too.

The idea of machining down standard McMaster-Carr brake linings sounds REALLY good, because it allows you to put in the maximum thickness you actually have room for.

Some really clever person might machine the lining in a way that puts more area in contact with the shoe... Rob Lees' drawing shows us clearly that only the "leading edge" of the brake lining is put into contact with the shoe. There may be a way to do the machining so that the lining is "parallel" to the shoe when engaged rather than when retracted??

[Larry Lyons]

Re: extreme frustration with Shinn brakes

Some really clever person might machine the lining in a way that puts more area in contact with the shoe... Rob Lees' drawing shows us clearly that only the "leading edge" of the brake lining is put into contact with the shoe. There may be a way to do the machining so that the lining is "parallel" to the shoe when engaged rather than when retracted??

I am not an engineer here but I beleive if machined and adjusted correctly almost the entire shoe will come in to contact, because of slight deformation, with the drum under load. Most brakes around the world in use today work on a very similar principle. Larry

[John Sowles]

Re: extreme frustration with Shinn brakes

I probably should not pile on Skybound but there does seem to be a pattern here. I ordered a set of new shoes and paid up front by credit card. This was a couple of years ago. Conversations with them asking when they'd be shipped were very pleasant and I was probably too patient. After a year and half, I finally gave up and wrote off the $138 or so. Now reading this, I think I took the less frustrating path. A shame as it sounded like the folks there are trying to support older A/C.

[Robert Lees]

Re: extreme frustration with Shinn brakes

I am not an engineer here but I beleive if machined and adjusted correctly almost the entire shoe will come in to contact, because of slight deformation, with the drum under load. Most brakes around the world in use today work on a very similar principle. Larry

My engineering self thinks you are correct, Larry. The greater the brake pressure, the more shoe comes into contact with the lining, because the shoe flexes (each shoe is basically "fixed" at one end).

Mr Shinn knew his stuff.

I'm sad that poor service is being received from Skybound; perhaps folk should try Donna Losey (Partsangel).

[Hank Jarrett]

Re: extreme frustration with Shinn brakes

Maybe the group should approach Skybound (with an attitude of "let us help you fix this", not a "what the heck is wrong with you guys"). We have the talent and knowledge in this group to provide all of the manufacturers with some help so they can serve our needs better. They want our money. We want good products. We should be able to work with them (all of them). Anybody know who their manufacturing engineers are?
Hank

[Larry Lyons]

Re: extreme frustration with Shinn brakes

Maybe the group should approach Skybound (with an attitude of "let us help you fix this", not a "what the heck is wrong with you guys"). We have the talent and knowledge in this group to provide all of the manufacturers with some help so they can serve our needs better. They want our money. We want good products. We should be able to work with them (all of them). Anybody know who their manufacturing engineers are?
Hank

Hank, I could not agree more with you here. I/we need the help! Larry

[Hank Jarrett]

Re: extreme frustration with Shinn brakes

Several good mechanics, FAA guys, machinists, manufacturers and engineers on this group. I'm open to helping. Any manufacturer who wants our help only needs to contact us.
Hank

Going to be off line for about a week soon on travel. If no response, I'm not ignoring you, I'm at sea.