Pull start repair.

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B Mann
Posts: 37
Joined: Tue Sep 17, 2019 8:07 pm
Location: Northern Indiana (Michiana)

Re: Pull start repair.

Post by B Mann » Sat Dec 28, 2019 11:52 pm

Harold_V wrote:
Sat Dec 28, 2019 3:04 am
I'm having more than a few doubts that you would be able to weld on the shaft and have the thread end up perpendicular. I also don't think that the amount of wear you have would be a problem to sleeve. There's not a lot of stress on that part when it's used, so breaking isn't much of a concern. I also think that, with care, you could machine the shaft in a lathe, assuming you have enough swing. That would be preferable to attempting to true it up with a rotab, although I suspect either method would yield acceptable results.
Well, very new Newbie here. I have more than enough swing on the lathe. I can't figure out how to mount it. I was thinking of using a short piece of round stock, drilling it, tapping it to fit the thread on the shaft. Put the new cut stock in the 3 jaw chuck then find the center on the back side. With that I can drill and tap it. Then put a piece of threaded stock or bolt in it. Then flip back around to put that in the 3 jaw chuck. Seems to be a lot of work. Or is there something much easier I am missing?? The cover is tapered like a cone, plus it is not round.

Once that is done it would be nothing to turn it to clean it up.

B Mann
Posts: 37
Joined: Tue Sep 17, 2019 8:07 pm
Location: Northern Indiana (Michiana)

Re: Pull start repair.

Post by B Mann » Sat Dec 28, 2019 11:59 pm

carlquib wrote:
Sat Dec 28, 2019 2:33 pm
I've made repairs like this. I clamped the housing down on the mill and used a boring head with a left hand tool to turn the shaft down. I next made and pressed/loctited a sleeve on the shaft. I think Harold's idea of making an oillite bushing to bush the clutch assembly is a good one.
What is this assembly from? The last one I did was from a Honda 110 three wheeler.

My name is Brian and I'm a toolaholic.
This is from a Honda 250. The problem is it is so worn that the pulley is riding sideways against the flywheel. It is getting the pulley hot from friction. You can see the wear mark from the flywheel in the top of the picture of the pulley by itself.

Harold_V
Posts: 18041
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Pull start repair.

Post by Harold_V » Sun Dec 29, 2019 1:41 am

B Mann wrote:
Sat Dec 28, 2019 11:38 pm
I guess I was leaning toward a weld up and machine down because I have been welding for decades and it is what I am familiar with. The mill and lathe are new tools to me.
Chuckle. Yeah, when the only tool you have is a hammer, everything looks like a nail.
OK, the oversized bushing sounds good. I am thinking I would want to clean up the pulley and press the bushing in that. Hard to see in the pictures, but the center of the pulley is worn so thin it is beginning to crack.
You actually have a respectable idea, at least in my opinion. But what I'd do is bore to clean up, then silver solder a sleeve inside. That should restore integrity. Pressing in a bore that is already compromised isn't likely to yield success (the crack you spoke of). Make sure the crack is clean, so solder will penetrate, assuming you flux well.

The sleeve bore would be well undersized, so you could then mount the pulley and bore to size, ensuring concentricity and perpendicularity. It stands to reason that getting the entire bore free of oil and dirt would be important, but I suspect that, as a weldor, you know that already.

In your succeeding post you said that the housing is tapered, so there's no way to grip it. I agree, and it's obvious from looking at the picture, although that fact had escaped me.

That said, I highly endorse the idea of using a boring head (suggested by carlquib), mounting the part in a mill. it can be clamped to the table, although that may take a little creativity, as your clamps will get in the way of the boring head. If the flange is parallel to the mounting surface, it's a perfectly acceptable way to make the setup. Once setup, you can find center of the shaft with a DTI, then turn the shaft to the desired diameter. In this case, you'll have to be happy with the material from which the shaft is made, as you now won't be able to use a hardened sleeve. Considering the condition of the pulley bore, this is likely the better choice, however.
I am familiar with oilite bearings. It sounds like a good idea. Like you said it is a metal on metal situation. I am not sure how thin you can go. if I clean up the shaft and pulley I am looking at about .170 room. By the time I put a bushing in the pulley, how thin of a oilite bearing can I use before I destroy it just trying to machine it???
All depends on how you hold the bushing. It is highly recommended that you have material longer than the bushing length, so you can grip the material without introducing any stress. You'd grip the piece, then drill (undersized) then rough turn. You would then bore to size, and turn to size. I'd recommend a couple of thou press fit in the pulley, keeping in mind that the thin wall of the bushing is going contract when it is pressed in to the pulley. You'd want to start out with a bore size that is about .003" larger than the shaft size (which has been polished smooth). The bushing will collapse at least 1½ thou, leaving you with at least a thou clearance. I suspect it is important that the assembly be free wheeling at speed, so don't shoot for a tight fit with the pulley on the shaft.

Don't try to work on the bushing once it has been parted. Thin walls such as this don't respond well to being gripped unless you can grip them uniformly (like with the proper sized collet, or pie soft jaws). That's why you make it in one operation, then part it off.

You should be able to make a bushing with a wall thickness of .03" and expect acceptable results. If you find it can be thicker, all the better.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

B Mann
Posts: 37
Joined: Tue Sep 17, 2019 8:07 pm
Location: Northern Indiana (Michiana)

Re: Pull start repair.

Post by B Mann » Sun Dec 29, 2019 1:40 pm

Harold_V wrote:
Sun Dec 29, 2019 1:41 am
OK, the oversized bushing sounds good. I am thinking I would want to clean up the pulley and press the bushing in that. Hard to see in the pictures, but the center of the pulley is worn so thin it is beginning to crack.
You actually have a respectable idea, at least in my opinion. But what I'd do is bore to clean up, then silver solder a sleeve inside. That should restore integrity. Pressing in a bore that is already compromised isn't likely to yield success (the crack you spoke of). Make sure the crack is clean, so solder will penetrate, assuming you flux well.

H
I guess the better word was to insert the bushing. My plan was to clean up the pulley and very lightly press the bushing in. Enough to hold it. (then solder or braze in place) I do have some silver solder. Thanks for your help and will let you know how it turns out. I am not in a hurry so will get to it sooner or later.

BTW all the parts are covered in heavy grease. They will need a good cleaning. The way it was made, (metal on metal) it has lasted almost 30 years. So it may outlast me if I do it half as well. Haha

Harold_V
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Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Pull start repair.

Post by Harold_V » Mon Dec 30, 2019 2:30 am

Sounds good to me. I'll keep a good thought that the process works well and you achieve success.

One thing I'd suggest, though. Be certain to allow clearance for the silver solder. If you use a light press, it most likely won't penetrate. Give it a couple thou clearance, then if you hope to keep the bushing location, you might achieve the goal by putting a few shallow dimples (sharp center punch) around the bushing, near each end. Well placed, they'll allow the bushing to remain fixed, and still allow the silver solder a space to run. The slightest tap with a light hammer should provide enough of a burr to perform the required function.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

John Hasler
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Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Pull start repair.

Post by John Hasler » Mon Dec 30, 2019 8:30 am

Scoring the bushing rather than dimpling it will provide channels for the solder.

JackF
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Location: Caldwell, Idaho

Re: Pull start repair.

Post by JackF » Mon Dec 30, 2019 3:37 pm

This is just a thought, if you cold mark on the outside cover where the shaft is, you could cut a hole in the outside cover big enough for the shaft to pass through.Then you could make a patch to cover up the hole and screw it to the cover. :roll: Like I said, just a thought. :D


Jackl

Harold_V
Posts: 18041
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Pull start repair.

Post by Harold_V » Mon Dec 30, 2019 8:54 pm

John Hasler wrote:
Mon Dec 30, 2019 8:30 am
Scoring the bushing rather than dimpling it will provide channels for the solder.
My concern is the comment about the existing crack. While the channels would allow solder to flow from one side to the other, and interference would preclude the solder spreading, which, in this case, tends to defeat the idea of silver soldering. My thoughts were that the solder would tend to fuse the items fully, so they'd regain integrity. With channels, that may or may not occur. The dimples present virtually no interference, yet permit what could be considered 100% coverage. Thus my recommendation for clearance.
Truth be told, there is no need to do anything, aside from resting both items on a fire brick, which will orient the bushing lengthwise.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

John Hasler
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Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Pull start repair.

Post by John Hasler » Mon Dec 30, 2019 9:37 pm

I had in mind clearance plus scoring. The burrs would provide some small amount of interference with less risk of deforming the bushing.

Harold_V
Posts: 18041
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Pull start repair.

Post by Harold_V » Tue Dec 31, 2019 2:55 am

John Hasler wrote:
Mon Dec 30, 2019 9:37 pm
I had in mind clearance plus scoring. The burrs would provide some small amount of interference with less risk of deforming the bushing.
I didn't understand your idea but I do now. Unless the scoring was short, it offers the opportunity for a dam, preventing the solder from flowing around the bushing. Not a problem if one applies solder between each score, but it may not be obvious what you haven't. The tiny punch marks wouldn't do that, and they're so insignificant that they wouldn't deform the bushing. All that needs to be done is to raise the surface by a thou or two. The bushing most likely would palm press, flattening the miniscule punch marks. I'd likely favor that over scoring for that reason.
I'm not suggesting scoring wouldn't work---I just feel it offers an opportunity for failure.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

John Hasler
Posts: 1423
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Pull start repair.

Post by John Hasler » Tue Dec 31, 2019 10:51 am

I see your point. He could do short scores near each end, but I guess that really isn't much different from punching (I'd put the bushing on a shaft for a backstop while doing either).

I like your last suggestion best, though.

B Mann
Posts: 37
Joined: Tue Sep 17, 2019 8:07 pm
Location: Northern Indiana (Michiana)

Re: Pull start repair.

Post by B Mann » Fri Jan 03, 2020 8:53 pm

JackF wrote:
Mon Dec 30, 2019 3:37 pm
This is just a thought, if you cold mark on the outside cover where the shaft is, you could cut a hole in the outside cover big enough for the shaft to pass through.Then you could make a patch to cover up the hole and screw it to the cover. :roll: Like I said, just a thought. :D
Jackl
I kind of gave that a thought. It is hard to see in the 3rd picture. The shaft has a big flange on it. (about the size of a 50 cent piece) The flange is spot welded to the large "pan" in the bottom of the picture. Then the pan is spot welded to the outside of the case. (sandwiching the shaft in the middle) To take it apart you would have to cut out about 15 spot welds. I don't think they ever thought this would be a repairable item.

The lathe was a great idea, but no way to mount it. I am going to start with the mill. I am new to machining. I have a hold down kit on order. I have a 30% chance of it arriving tomorrow. I want to hold the cover down very secure.

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