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capav8
05-08-2011, 11:23 PM
Greetings,
I need to assemble the trim system. I only have the forward pulley. No bolt, washers or crank. So I need to make the missing parts. How does the pulley and crank go together. I see the groove in the top of the pulley for a key or the like. If I look at it long enough I'll come up with something, but needs to look like it belongs there. Obviously some pics are always helpful. The aft portion is fully intact.

Thanks,
Jim

aktango58
05-09-2011, 12:40 AM
pin, not bolt, is what the pulley slides onto, it comes out of the frame, roll pin holds pulley, spring, cover and handle then go on, roll pin through handle and rotating pin, cover slides back with spring pressure to hide the roll pin through handle.

The roll pins are parallel to each other.

Mark_B
05-18-2011, 12:08 PM
2380
Greetings,
I need to assemble the trim system. I only have the forward pulley. No bolt, washers or crank. So I need to make the missing parts. How does the pulley and crank go together. I see the groove in the top of the pulley for a key or the like. If I look at it long enough I'll come up with something, but needs to look like it belongs there. Obviously some pics are always helpful. The aft portion is fully intact.

Thanks,
Jim

I just upload a PDF file.
see attachment

STABILIZER TRIM HANDLE & PULLEY


2380

Darrel Starr
05-18-2011, 12:36 PM
The original design tends to wear the tabs on the frame quickly -- so several SCs around here now have oilite bearings as shown.
Darrel

2385
As Modified
2387
Close Up
2388

kevin
05-18-2011, 01:50 PM
to back up the oilite bearings, I installed a completely brand new trim system with all new parts, including the tabs that the crank pin goes thru. Mine was wallowed out. I purchased all the parts from Univair. I greased the crank pin with white grease when I assembled it. After assembly, it was so stiff, from metal on metal, I could barely move it. I took it all apart(something I didn't want to do because of the roll pin holding everything in), used Darrel's schematics and installed the oilite bearing. It is now as smooth as butter. I will never install another trim system again without that oilite bearing.

behindpropellers
05-18-2011, 02:06 PM
If you like Oilite you should check out IGUS bearings.

Much lighter.

http://www.igus.eu

tempdoug
06-01-2011, 11:17 PM
Darrel, are those the 1/4 inch long or 3/8ths long bushings?

Darrel Starr
06-02-2011, 10:41 PM
I used the 1/4 inch long Oilite FF520-15 bushings. I purchased them from Aircraft Spruce:
http://www.aircraftspruce.com/catalog/hapages/flangedbushings.php

Here is what the actual parts look like laid out and assembled:
2525
2526
2528
2529

tempdoug
06-03-2011, 11:48 PM
Darrel, whats your technique for drilling holes in the pin straight and in the middle?

kevin
06-04-2011, 11:42 AM
I took mine to a machine shop. I told them what size hole I wanted it and where I wanted it. They said no problem...

Darrel Starr
06-04-2011, 08:40 PM
tempdoug: I have a small inexpensive Chinese made Mill-Drill as shown with a good 6 inch machinist's vise (hidden under the white board I use as a shelf when the Mill-Drill is not in use):
2535
I put the pin in the vise on machinists parallels so the pin will be horizontal. I center the Mill-Drill head with a a small pointed tool, an Awl, that I have for the purpose. I spend a lot of time with a finely scribed 6 inch scale to position the center of the tool as close as possible to the centerline of the pin. Then I chuck up an 1/8th inch diameter end mill cutter. With this little cutter I mill a flat spot on the pin where the hole will be. That is a necessary step as a small diameter drill bit on the pin's curved surface will just bend off to one side. Then I drill a starter hole with a 1/16th inch diameter bit before chucking up the final size bit. If I am careful enough I get a hole pretty much dead nuts.

Darrel Starr
06-04-2011, 09:00 PM
And this is the cabin view of the trim crank area -- note no spring, nothing grinding against the cover plate.
2536

aktango58
06-04-2011, 10:05 PM
Darrel,

Why not punch the hole with the endmill? Drill bits walk... no matter what. By using an end cut mill you could be even more precise.

Asking to learn.

Gordon Misch
06-04-2011, 11:04 PM
With the pin horizontal, place a steel rule on top of the pin, crossways. Gently run a center drill down onto the top of the rule, with the spindle turning, and move the work back and forth until the rule is horizontal. Real quick way to get pretty darn close.

The exact way - use an edge finder on the side of the pin, move the workpiece half the pin diameter plus half the edge finder diameter (probably 0.100"). OR use the edge finder on the vise jaw and move half the pin diameter minus half the edge finder diameter. You're exactly on center (requires a milling machine to dial in the correct distance).

Start with a center drill - it won't walk - no need to make a flat spot. Did this a few million times (it seemed) when I was in the machine shop business. A boyhood neighbor who was a tool maker for Convair taught me the ruler trick - works slick, and is practical with just a drill press.

Darrel Starr
06-04-2011, 11:21 PM
aktango58 -- the times I have tried to end mill with a small diameter cutter through a relatively thick piece, it seems to be very slow going, pulling the cutter out to get chips often. That's why I switch to a drill.

12 Geezer -- I'm not a machinist, I just stumbled on the technique above. I am using the scale just as you describe with the awl. I have center drills, just never considered using one this way -- I'll try it next time. I have an edge finder but this Chinese table has some play in it which makes using the edge finder seem no more accurate than just using the scale technique, learning as I go...

aktango58
06-04-2011, 11:28 PM
You can also mount a dial indicator on the table against a spot on the drill/mill head. As the table moves in and out it should read the amount of movement; much more accurate and will take out the slop...

However, always go to your measurments/setting turning the same way on the dials so that the backlash is on the same side of your cut every time....

Gordon Misch
06-04-2011, 11:40 PM
Darrel,

Why not punch the hole with the endmill? Drill bits walk... no matter what. By using an end cut mill you could be even more precise.

Asking to learn.

Actually George, it doesn't work out that way.

First of all, by starting with a center drill in a rigid machine, the bit will not walk. Once the hole is started - a good dimple is enough to get a jobbers drill to track. If the jobber drill is sharpened symmetrically, that is.

Also end mills, by design, are side-cutting, whereas drill bits are not. Any eccentricity in the spindle / chuck assembly, or looseness in the spindle / quill assembly will result in the endmill cutting oversize and perhaps off-center.

The correct tool for this task is a drill. Start it with a center drill, then an undersize bit, then the desired size bit. If a real accurate diameter is needed (isn't for roll pins), then drill slightly undersize and ream.

Hope this helps - -

Gordon Misch
06-04-2011, 11:49 PM
Darrel,
All lead screws (except expensive ball screws) have backlash. The idea in using the dial on the screw is to work toward the desired position on the dial using the same rotational direction from one location to another. Often this means going past the desired location, then reversing to the desired dial reading. It's possible to be very accurate this way. Using a dial indicator as George mentioned is also good, but only for relatively small displacements (dial travel limitations). Digital readouts are WAY COOL though!!! I had them on my horizontal boring mill - really slick. (George - is Mike Bell still using that mill? It was German made and a terrific machine - but not the easiest thing to maintain - probably at least a dozen electro-mechanical relays in the control box).

aktango58
06-05-2011, 12:15 AM
Yes Gordon, he is!

Right on on the center drill... I was thinking strictly of jobber bits, which most people think drill strait.... plunge mill is actually better that many bits I have seen.

Ream is correct, but this is not that critical, is it.

Mike is teaching at the University now, and the shop is up for sale....

mike mcs repair
06-05-2011, 12:27 AM
.....
Why not punch the hole with the endmill? Drill bits walk... no matter what. By using an end cut mill you could be even more precise.


settle down everyone...

its just a hole for a chunk of bent welding rod to go through....

that's holding a handle whose holes will be wobbled out HUGE in no time......
no Rolex effort justified or required...

relax... focus your efforts where they will count :-)

tempdoug
06-05-2011, 06:16 AM
The tabs that are welded to the fuselage that hold this pulley in position, would you know how thick they are where the pin goes through?

tempdoug
06-05-2011, 06:59 AM
http://javroninc.com/media/products/thmb_Product_38.jpg (javascript:dopop('http://javroninc.com/media/products/Product_38.jpg');)ball brg one

aktango58
06-05-2011, 04:30 PM
settle down everyone...

its just a hole for a chunk of bent welding rod to go through....

that's holding a handle whose holes will be wobbled out HUGE in no time......
no Rolex effort justified or required...

relax... focus your efforts where they will count :-)


Welllllll Mike, would that be an FAA approved welding rod8)


But the principal is the same, drilling a shaft for the trim, or cutting a hole for attaching Ski fittings to your axel...

If we can discuss ways to do this on parts that are not so critical, maybe we will remember to practice on non critical parts instead of things like crank shafts:oops:

But you are correct, some parts are not worthy of rolex precision, but knowing hot to get that accurate is cool!

Darrel Starr
06-05-2011, 06:26 PM
It helps to slightly bend the piece of welding rod that you make into a pulley pin.

tempdoug -- Is that a Smith part? Very nice.

kevin
06-05-2011, 10:45 PM
Not only does it help to slightly bend the part to get it started but I ground the tip to a point.

Darrel Starr
06-05-2011, 10:53 PM
Kevin -- I did too.

flybynite
06-06-2011, 08:14 AM
The tabs that are welded to the fuselage that hold this pulley in position, would you know how thick they are where the pin goes through?

Tempdoug, They are .063" folded over to double thick at the end where the pin goes through.

Wayne

tempdoug
06-06-2011, 09:23 AM
Thank you Wayne. The pulley is .375. So outside to outside should be around 5/8ths, then. I have no print for that.

tempdoug
11-19-2011, 08:33 PM
bump again

cruiser
11-19-2011, 09:05 PM
Thanks tempdoug, My guess is that pin is too long to do this on a covered airplane but on a re-cover this looks like a must do item. Jim

tempdoug
11-20-2011, 08:41 AM
Im going to try and do this to mine in a month or so, on a covered plane. Going to have to look at things close before i drill out to 1/2 inch if the pin will make the corner or not. With the 1/2 inch hole it will give it a little extra going around the corner. And maybe a little pulling without bending on the outside tab. Let you know if it works or not. Wish i had something bare close by to look at or if anyones done it covered? doug

Steve Pierce
11-20-2011, 08:42 AM
You have to slit the fabric for the pin to slip out.

Darrel Starr
11-20-2011, 09:07 AM
A friend made this change to a covered plane by adding a round inspection cover to the fabric - no one even notices it.