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Fitting cotter pins

Old 08-25-20, 06:01 PM
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63rickert
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Fitting cotter pins

Is there any on this forum who know how to file cotters and can explain it?

Two LBS have tried and failed with a Var #7. Both times young mechanics who may never have used that tool before. It is covid time and I cannot walk into shop and use the tool myself. My main wrench for a long time was Ron Boi and his shop is closed for good. At another shop Iíve known proprietor fifty years but making an appointment with him is simply impossible, he does not know himself where he will be five minutes hence. The only certain solution is driving 300 miles round trip to Yellow Jersey.

The best description heard so far is of Raleigh cotterpins going into Raleigh cranks and Raleigh spindles. Almost clicked or snapped into place, it is said, and you knew it would work. One light tap with hammer, snug up the nut and it never failed. File it so it feels like a Raleigh cotter. During 1960s. Well, I never had that shop experience in 1960s and donít know the feeling.

So far have filed until the ramp of pin can be felt solidly engaging the flat on spindle. With thumb pressure on the pin, no hammering, no nut, the crank does not move. Remains solidly in position while moving bike around shop. But that is not good enough. Hammer it home, add the nut, on test ride it creaks instantly.

Please do not tell me about the Bikesmith tool. Already tried that and did nothing but trash a cotter.

Going forward it is not going to be possible to ride my bikes if there is no way to put a crank on. This is not about getting it on there somehow and having it look presentable. It is about having bikes to ride and to use daily.

Another good description is archived at the Dave Moulton blog. English schoolboy racers used to refit cotters before every big race. Not all of them could have been mechanical savants. They re-used cotters over and over, never had them come loose, only rarely damaged them and needed to replace. But Dave never gets to exactly what they did, except to say they filed down the shiny spot. He sort of assumes the reader already knows a whole lot. Dave is not available for questions. To get to the point where there might be a single shiny spot sounds like a dream.

So far I have five dead cotters and no bike.

No pictures. Canít post them. Complete Luddite. Will experience shock if this text posts at all.
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Old 08-25-20, 06:13 PM
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...is your question about filing new ones to fit, or is it about getting the old ones out without trashing them, so they can be re-used ? I'm unclear from reading your post, and they are different animals.
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Old 08-25-20, 06:21 PM
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Old cotters are hard and can be reused. I do it. New cotters are soft, maybe not a great idea to reuse them.

For my technique, I coat the flat of the cotter with Sharpie. I put it in 98% there. I take it out. Where the Sharpie rubs off is a high spot. File there. Rinse and repeat.
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Old 08-25-20, 06:58 PM
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Originally Posted by iab View Post
Old cotters are hard and can be reused. I do it. New cotters are soft, maybe not a great idea to reuse them.

For my technique, I coat the flat of the cotter with Sharpie. I put it in 98% there. I take it out. Where the Sharpie rubs off is a high spot. File there. Rinse and repeat.
Understand the principle. Already did that. Doubt I am attempting to execute anything at all like what you are doing. Just not getting the file to address only the indicated spots. It all gets cut off.

About the 98% part. What I am doing is tapping it once lightly with a hammer. Little enough it will come out just as easy to look at progress (hah!). Problem is that technique barely shows anything. To get a clear print it has to be fully assembled and test ridden. I am still hammering fairly hard on assembly. And then it is hard to get out and the threads mash.

I am not a mechanic. I have a head full of bicycle rubbish gathered over sixty odd years. Doesnít mean my hands do it or my eyes see it. Need all the pieces plain.

Oh. How far, how deep, are we going? With each repetition the pin gets thinner. Or should it be such a fine file we get dozens of tries?

If you have old 9.0 pins I am buying.

And thank you.
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Old 08-25-20, 07:00 PM
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Iíve used the Bikesmith press and cotters, the press is OK but I replaced it with a Park cotter press that works better. I have never had to file Bikesmith cotters, if your spindle is in good shape you shouldnít have to either unless you are buying the cheap flattened cotters that tend to bulge. I put a little anti seize compound on the cotter making sure to keep it off the machined flat and use the park tool to press it in. You should never use the nut to pull the cotter in place. Once pressed into place screw on the nut and snug it up, ride the bike, press the cotter again, snug the nut, that should do it.

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Old 08-25-20, 07:07 PM
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BITD one of the shop tools from the cottered crank era was a cotter holder, so you could clamp it in your bench vise,
in the holder, an take out a file, and file the taper to have a perfect fit..


tap on it with a hammer then slug up the but , don't try pulling it tighter with the nut, use a hammer on the other end..





...

Last edited by fietsbob; 08-25-20 at 07:11 PM.
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Old 08-25-20, 07:10 PM
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First of all, if you run out of cotters, let me know what diameter and/or the make/model of crank, I can probably help. I have a wide assortment of NOS stuff, but not because people PM'ed them to me as I've requested above my avatar for years. People be stingy with them cotters!

That said, proper removal, proper fitment should be done with a legit cantilever/bypass press like the VAR07. There's a trick to using a VAR07, and it seems not many these days are familiar with the tool Go figure! There's an adjustment to be made using the bolt coming out of the top of the tool on same side as the short arm. The biggest mistakes I find newbies making include 1) Hyper-adjusting the tool's jaw adjustment bolt so the tool clamps too hard too fast, which bends or mushrooms the cotter leaving the threads toast or leaving you drilling out the remnants, or 2) Not getting the jaws square over the cotter before clamping, which also often leads to bending the threaded side, or 3) They don't have the open end of the jaw over the blunt end of the cotter, so it's pressing the cotter in, not out .

My advice to newbies is this. Get a VAR07 or find someone with one. Spin the adjustment bolt out significantly. Clamp the jaws correctly over the cotter loosely. Spin the adjustment bolt on the VAR07 down until the jaws make contact firmly with the cotter, where the split side of the jaw is making clean contact with the crank arm, and the press end is firmly on the threaded end. Now it's tight but not yet tight enough to press the cotter out, take the VAR07 off the crank, spin the adjustment bolt 360ļ to close the jaw a little more. Now try to press out your cotter with the VAR07 perpendicular to the crankarm, so it's nicely square over the cotter. If you're still not able to press it out, pop off the VAR07 again, spin the adjustment bolt down 180ļ to tighten a little more, then try to press out again. Repeat 180ļ tightening of the jaw until you press out. By going light and working up to a firmer jaw stance, you'll have a better chance of pushing the cotter out, potentially in a condition where it can be re-used. This is what I tell newbies to do so they don't make a mess of things. You start to get a feel for what's right with time and experience, the reality is you only need half an inch of actual movement to generate the force required for cotter removal, so you DO NOT want the arms of the VAR07 to be really wide-open. With the arms of the VAR07 wide open, you're going to work 10x as hard to close the arms. Use your simple machine, leverage, to do the work for you!

Proper fitment is also a process. In my opinion, this process involves pressing in and pressing out the cotter multiple times. Press your cotter in until it stops. Pop it back out. Look where exactly on the wedged face it's making contact to know where to file the face of the wedge so the cotter fits nicely in. I have a proper cotter vice, but I used to use the magnetic rubber covers back in the day to hold the cotter in a bench vice so I'm filing the face perfectly straight.. I've seen guys who can just take a cotter in their hands and run it down the file, and I met one guy who used a disc sander! After filing the face, press in again. If it's not quite in the correct depth, pop it out again, look at your mark where it bottomed out, repeat filing the face. I normally aim to press mine in so only 3mm-5mm(ish) of the blunt end is exposed after fully pressing in.

BTW, the face marking method @iab describe is excellent, especially if you don't do it often, or your eyes are going to hell like mine, it's almost like using a guide coat with body work, or marking blue for metal work. Black sharpie works fine.

When I'm doing my final press, I'll sometimes give the VAR07 adjustment bolt another quarter or half turn to really press it in there. Again, you don't need much!

Top it off by installing the washer and cap nut, then tightening fully. NEVER use the dome nut to "pull" the cotter into place. If you were able to generate the force required, you'll probably strip the threads first, making your cotter worthless. I know, there are people who will swear they've been able to do this, but if it's a new cotter, chances are it'll wiggle out with some riding.

Just be careful, don't over-file. You can't add metal back.
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Old 08-25-20, 07:18 PM
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PS - I also can't iterate enough you must have the proper diameter cotter for your crankset and spindle. It helps also to make sure the cotter you're using isn't over-faced/over-tapered for your crankset. If, on your first press-in, the cotter bottoms out, it's either over-faced for this application, or it's possibly not the correct diameter.
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Old 08-25-20, 07:21 PM
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Last iteration has the whole ramp twisting off to the side. No longer a question of high spot, am looking at turning three dimensions into two. Which is quite a trick. Not sure if this pin can go any further without cutting threads. A new pin tomorrow.
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Old 08-25-20, 07:27 PM
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Bikesmith tool shoved a big gall of metal up the wedge face of pin. Not even going to try to figure that out.
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Old 08-25-20, 07:29 PM
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Originally Posted by 63rickert View Post

No pictures. Canít post them. Complete Luddite. Will experience shock if this text posts at all.
You have over 1600 posts, why would this one posting shock you?

What bike, crank, cotter size, spindle, etc do you have? Where did you get the cotters?

You need a cotter press to remove AND to install. This is my go-to guy....

BikeSmith Design and Fabrication
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Old 08-25-20, 07:32 PM
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I swore I created a thread on BF once showing how I file cotters. It's killing me I can't find it.

Bikesmith used to sell cotters and may still. Closest I can find to explaining filing. Like, go here: https://www.bikesmithdesign.com/CotterPress/cotters.html

Look at the picture of the three 9.5mm cotters. The one on the right is what most of my machined cotters looks like. I'll give my first press. If it doesn't go in fully, when I pop it back out, I can see how far down the face it's hanging up. Then I'll start filing so it's moving closer to the face of the middle cotter, then press in again, if it doesn't seat far enough, I'll pop it out and check where it's hanging up. Rinse/repeat. by the time you get to the facing you see on the far-left 9.5mm cotter in that pic, I'll be surprised if you're not seating fully where you need to be
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Old 08-25-20, 07:35 PM
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Originally Posted by 63rickert View Post
Understand the principle. Already did that. Doubt I am attempting to execute anything at all like what you are doing. Just not getting the file to address only the indicated spots. It all gets cut off.

About the 98% part. What I am doing is tapping it once lightly with a hammer. Little enough it will come out just as easy to look at progress (hah!). Problem is that technique barely shows anything. To get a clear print it has to be fully assembled and test ridden. I am still hammering fairly hard on assembly. And then it is hard to get out and the threads mash.

I am not a mechanic. I have a head full of bicycle rubbish gathered over sixty odd years. Doesnít mean my hands do it or my eyes see it. Need all the pieces plain.

Oh. How far, how deep, are we going? With each repetition the pin gets thinner. Or should it be such a fine file we get dozens of tries?

If you have old 9.0 pins I am buying.

And thank you.
I use a cotter press to get the 98% there now, but I have used a hammer in the past. That is when I ruined some new "soft" cotters.

Always check flatness after a few file strokes. You can't just file the "high" spots, needs to be blended on the entire flat side. Also, put a cotter onto the spindle without the crank arm, it helps visualize what it in contact and what is not.

And sometimes, you need to make your own "tricks" through trial and error. You got to do it wrong 10 time before you get it right.
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Old 08-25-20, 07:37 PM
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Oh, and I found this, it's randyjawa 's old Geocities guide to filing cotters - I don't recommend going to that page though, it kept trying to hijack my computer. Anyway, maybe this info helps?


Originally Posted by randyjawa's Geocities page




More often than not, the cotter pins that secure crank arms to bottom bracket spindles must be filed before they will properly fit. There is a problem associated with doing this.

If the cotter pins are not filed exactly the same amount and at the same angle, then the crank arms will not be spaced at 180 degree intervals. Of course, this would not be a problem if we could all afford to take the pins to a local machine shop for professional machining. However, there is at least one way that I know of that will greatly assist you in getting this task completed without a lot of guess work.

MATERIALS NEEDED:

1.0 One smooth flat file and handle
2.0 One small magnet
3.0 One bench vice
4.0 Some “shimming” material


THE PROCEDURE

1.0 Pick the cotter-pin up with a magnet. Ensure that the magnet is placed against the tapered flat on the cotter pin.

2.0 With the cotter-pin held to the underside of the magnet, carefully and securely clamp the pin in a bench vise. NOTE: As this stands, you will not be able to file anything off of the cotter-pin’s taper because it will be level with the top of the vice jaws.

3.0 Loosen the vice jaws enough to allow the cotter-pin to be lifted slightly. Slip two equal thickness THIN shims in between the magnet and the top of the vice jaws. Carefully tighten up the vice jaws and do a visual check to make sure that all is well. Now the cotter-pin taper will sit slightly above the tops of the vice jaws.

4.0 Begin filing the cotter-pin taper. Care must be taken to do this properly as follows:

4.1 Push the file forward with a smooth stroke ensuring to hold the file parallel to the tops of the vice jaws. As you approach the end of the stroke LIFT the file up and away from the cotter pin (this helps to prevent rounding off the tapers).

4.2 Continue this process until you begin to feel the file slide on the vice jaws (the file will not damage the vice jaws if you are careful).

4.3 Continue doing this until the file no longer feels as if it is cutting the cotter pin taper.

4.4 Using the same two shims, repeat this process for the other cotter-pin.

5.0 Install the crank arms with the newly filed cotter-pins. Gently tap the cotter-pins into place (do not over-do it as the pins might have to come out for more filing if they do not engage adequately).

6.0 With the cotter-pins temporarily installed, look to see if the pin has reached most of the way through the crank. The target here is to ensure that the cotter-pin is supported on both sides of the bottom bracket spindle. Do not go too far, just make sure it is partially engaged.

7.0 Once satisfied that the pin is in far enough and that the crank arm are parallel to each other, support the underside of the crank and cotter-pin assembly and drive the pin in good and tight with a hammer. NOTE: Be sure that the assembly is supported or you WILL do damage to the bottom bracket bearings.

8.0 Check to ensure that everything looks good and true, then install the cotter-pin nut and tighten it up. NOTE: The nut holds the pin in place. The nut must not be relied on to pull the pin into place.

9.0 Now ride the bike for a few miles the repeat the pin installation process. You will notice that the pin can be driven in a bit further.

10.0 Tighten the nut up again and you should be good for quite a while.

Good Luck!
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Old 08-25-20, 07:37 PM
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Originally Posted by francophile View Post
PS - I also can't iterate enough you must have the proper diameter cotter for your crankset and spindle. It helps also to make sure the cotter you're using isn't over-faced/over-tapered for your crankset. If, on your first press-in, the cotter bottoms out, it's either over-faced for this application, or it's possibly not the correct diameter.
It is proper diameter. One of few things I am sure of.

The pins donít go in far at all. First LBS attempt (with Var 7) the mark on pin was a little groove maybe 1mm up the face of the wedge. So nothing engaged but a little triangle about 1mm on side. This held and was quiet for not quite the whole ten mile ride home. Looking at other failed pins it sure does look like a whole lot more engagement but it doesnít last any longer.

I honestly would not know under facing from overfacing and the only thing I know to do with taper is to follow the original taper, just cut it deeper.

Hold onto those NOS pins until I get something to work with the expendable ones.
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Old 08-25-20, 07:56 PM
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Originally Posted by 63rickert View Post
Bikesmith tool shoved a big gall of metal up the wedge face of pin. Not even going to try to figure that out.
This sounds like the angle of the flat may have been too steep. Are you filing both drive side and non drive side pins the same amount and at as close to the same angle as possible?

Filing cotters is tricky indeed. Are these the originals, or are the ones that were installed initially still around? If you have one that previously worked intact, then you have a reference point.
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Old 08-25-20, 08:00 PM
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If you filed the cotter but the face is not completely flat, you can correct it by holding the file static against the vise and running the cotter along it.
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Old 08-25-20, 08:17 PM
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Originally Posted by francophile View Post
Oh, and I found this, it's randyjawa 's old Geocities guide to filing cotters - I don't recommend going to that page though, it kept trying to hijack my computer. Anyway, maybe this info helps?


That is interesting. It makes sense. I cannot even imagine getting all that set up in a vice nor can I imagine a vise of that perfection outside a machine shop.

In distant past mechanics I knew did this entirely freehand. Or with just a vice grip, or a basic bench vise, or just a file sitting on a bench top. Should have been paying more attention. Perhaps this is simply a very difficult job and there is good reason it has always been taken to a mechanic. Except there is no longer a mechanic.

Two very senior mechanics I have been talking to tell me that in any LBS once the Var tool first arrived no one ever filed a cotter again. Only exception being the most troublesome cases, then it got passed to the old guy. Who filed.
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Old 08-25-20, 09:43 PM
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...the only other suggestion I might be able to add to the above (especially in light of your filing two faces on a pin that requires only one), is that if you have the original profile from the ones that came out, and you have a bench ginder with a wheel big enough in diameter to have a flat side (and that is not terribly coarse in grade), certain less traditional mechanics have been known to very carefully and attentively shape the initial profile of the flat on the wheel's flat side. ou then finish it up with some light file dressing, which can be done as suggested by holding the file flat in a bench vise and moving the pin along it.

Someone will now come on and tell you why this is inadvisable, but it has worked numerous times for me, when I was too stupid to get the originals out undamaged.

Lately, I remove all cotter pins with that Bikesmith press, some 50/50 ATF-acetone as the penetrating oil, and a Mapp gas torch. I have yet to bend one since starting to do this. Maybe it's just coincidence. The heat and the penetrant really seem to help. Or maybe it's my belief system.
.
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Old 08-25-20, 11:30 PM
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Originally Posted by BFisher View Post
This sounds like the angle of the flat may have been too steep. Are you filing both drive side and non drive side pins the same amount and at as close to the same angle as possible?

Filing cotters is tricky indeed. Are these the originals, or are the ones that were installed initially still around? If you have one that previously worked intact, then you have a reference point.
I am trying to get one arm on one end of the spindle and have a bike to ride. The left arm came loose. Original installation lasted maybe 3000 miles and then creak. For time being it is a fixed gear and the right crank is still on there. And it is very flat around here. So I ride the bike with one crank arm. It gets old.

After I get the one crank arm attached and it stays attached will think about fancy stuff like two equal arms. Absolutely and completely no notion whatsoever what angle I should be aiming for.

LBS that did the first replacement has the original cotter. At time I took the bike from them I did think of asking for the old part back but it is covid time. Canít enter shop. Asking questions through masks. And the shops I know that pretend they can do this are down in the war zone where everything is all boarded up and the population in shell shock. So not possible to ask too much.
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Old 08-25-20, 11:55 PM
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Originally Posted by francophile View Post
Oh, and I found this, it's randyjawa 's old Geocities guide to filing cotters - I don't recommend going to that page though, it kept trying to hijack my computer. Anyway, maybe this info helps?

I donít currently own a vise because I have broken two. Have also broken a big shop vise and a friends machinist vise. Also have never been able to get anything to sit still in a vise ever. Donít you need machinists blocks and clamps and an array of fixtures and accessories to do that?

Completely serious about the above. I am that bad. And maybe I canít do this. Do know that this was once the standard of the world and hundreds of millions, maybe billions of bikes were operated this way. The supply of mechanical savants is not that big and neither is the supply of machinists shops that would want to diddle with cotter pins. Thinking of randyjawa technique and trying to see how it would be possible to do 0.002Ē or 0.005Ē at a time when the vises I am used to are not accurate to 0.020Ē. Or worse. Also thinking of Dave Moulton and his cohort who did this successfully many years with a file and a hammer. It gets done in 4th world shops where they use rocks.

I have enough mechanical sense to operate a QR as a cam and not a wingnut. I can mount tires every time, never touched bead jacks. I can stop a rim brake bike in the rain quicker and safer than nearly anyone on discs. I can do basic stuff. Some things are beyond me. If this is one of them I need a bike shop badly. Last one I asked they said they were not friends with cotter pins but they could figure it out. Leave bike two weeks. $100.
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Old 08-26-20, 03:16 AM
  #22  
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Geeze, I have not seen that old Geocities procedure for many years. In those days, when I published that procedure, my concern was getting the flats filed evenly, to ensure that the crank arms were parallel to one another. These days I rarely have to file cotters. Not sure why but that is the case with my builds. Also...

Get a press and learn how to use it. I built my own and have done a lot of cotter pushes with it over the years. In closing this post. let me say one thing...


I really, really like the appearance of cottered cranks sets. Got a NOS Legnano set a year or two ago. Came with a NOS bottom bracket and original cotter pins...


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Old 08-26-20, 03:23 AM
  #23  
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Originally Posted by 63rickert View Post
Just not getting the file to address only the indicated spots. It all gets cut off.

Oh. How far, how deep, are we going? With each repetition the pin gets thinner. Or should it be such a fine file we get dozens of tries?
Here are my two guesses -

a) Use a finer file, and as wide a one as you can find. The finer the file, the shallower the cut, and that makes it easier to just get the high spot.
There is a skill to filing a flat, you have to feel the contact area as you file, and move the file so the centre of the felt spot remains on the spot (which you also can't see) that is high; and that the plane of the cut stays constant. Sometimes I mount the file in a vice and push the part along it, especially if I don't want to mark the part by holding in the vice.

b) if you file too much the unthreaded end of the pin will poke out the hole and if you get it just exactly the right amount wrong the pin will lock the crank and the nut tightens as usual but it's not tight enough to ride.

And if the cotter is the cheap kind file it enough to get rid of the plating on the flat.

AND grease the pin. Somebody will want it to come out sometime.
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Old 08-26-20, 06:12 AM
  #24  
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Originally Posted by 63rickert View Post
I am trying to get one arm on one end of the spindle and have a bike to ride. The left arm came loose. Original installation lasted maybe 3000 miles and then creak. For time being it is a fixed gear and the right crank is still on there. And it is very flat around here. So I ride the bike with one crank arm. It gets old.

After I get the one crank arm attached and it stays attached will think about fancy stuff like two equal arms. Absolutely and completely no notion whatsoever what angle I should be aiming for.

LBS that did the first replacement has the original cotter. At time I took the bike from them I did think of asking for the old part back but it is covid time. Canít enter shop. Asking questions through masks. And the shops I know that pretend they can do this are down in the war zone where everything is all boarded up and the population in shell shock. So not possible to ask too much.
Without that drive side pin to compare, the task of matching the angle is much more difficult. I wonder if there is a fellow member near you who can assist. The reality of the times certainly makes this more challenging and I sympathize. What crank set are you using here? Maybe someone here has the same, maybe even spare pins?
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Old 08-26-20, 06:26 AM
  #25  
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@3alarmer
Originally Posted by 3alarmer View Post
.
..Lately, I remove all cotter pins with that Bikesmith press, some 50/50 ATF-acetone as the penetrating oil, and a Mapp gas torch. I have yet to bend one since starting to do this. Maybe it's just coincidence. The heat and the penetrant really seem to help. Or maybe it's my belief system.
.
Please so is your sequence for this apply heat, apply ATF/Acetone, apply press once cooled?
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