Gear Repair.

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Re: Gear Repair.

Post by Harold_V » Thu Apr 22, 2021 1:43 am

Bill Shields wrote:
Wed Apr 21, 2021 9:05 pm
There are suppliers other than Boston gear
Yep, Browning being one of them, but my experience thus far is that they tend to duplicate one another's stock, so that may not be a solution. Certainly worth investigating, though.

Indexing heads generally don't provide weird intervals, with 9°being one of the odd ones. A dividing head is unlimited, though. I'm hoping he means he has a dividing head, not an indexing head.

A guy could use a rotab with success, with care. Might take some creative setup, however.

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

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Re: Gear Repair.

Post by atunguyd » Thu Apr 22, 2021 3:34 pm

Something else to try, since it is only two teeth would be to braze up the gap, transfer the pattern of the missing two teeth onto it with a sharpie or something to that affect and hand shape it with a file.

I say this assuming you, like me, don't have an involute clutter and can't easily source one. It might be slow but it is only two teeth

Is this possible or am I oversimplifying it?

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Re: Gear Repair.

Post by AllenH59 » Fri Apr 23, 2021 9:25 pm

I have rotary table, with a 4 jaw chuck on it. I have the indexing kit for the table, although 9 degrees is not that difficult. I could turn an arbor for the gear in the chuck, and center it there. I would buy an involute cutter, I just need the number 3, I have considered a few repair techniques. Firstly, I am thinking it might be OK to mill a slot in the gear and braze or silver solder a chunk of steel into it, and that way I have steel teeth when I cut them. Secondly, fill it with brass and cut the teeth in them. I have a guy looking for the correct gear close to the source, and I will know sometime next week if one is located. I will not worry about it until then.

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Re: Gear Repair.

Post by johnfreese » Sat Apr 24, 2021 12:13 am

Check Flea Bay for 16DP gears.

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Re: Gear Repair.

Post by AllenH59 » Sat Apr 24, 2021 9:25 am

johnfreese wrote:
Sat Apr 24, 2021 12:13 am
Check Flea Bay for 16DP gears.
Nothing wide enough... this gear is 3/4 of an inch wide with flanges on both sides

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Bill Shields
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Re: Gear Repair.

Post by Bill Shields » Sat Apr 24, 2021 1:00 pm

Martin Gear?

They have 16 dp 3/4" face spur gears.

You may have to be a bit creative but something is better than missing teeth

I have fixed gears using the braze and shape method...not the easiest but when stuck in middle of nowhere with no spare parts and the need to get a turbine running -> you do what you can
Too many things going on to bother listing them.

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David Powell
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Re: Gear Repair.

Post by David Powell » Sun Apr 25, 2021 5:41 pm

I am rather surprised that no one has so far mentioned this other method of repair. Firstly file the two broken teeth down reasonably flat, then as best as possible find the centre of one tooth, obtain some brass screws diameter slightly above the thickness at the widest point of the teeth. then drill and tap for one screw as near as possible to one edge of the gear, then file or grind away about a third of the inside edge of the screw you just fitted and drill and tap for another screw as close to the first as you dare, even cutting a trace of thread on the side of the already filed screw if you can
Repeat till you are across the gear. Repeat for other teeth. cut screws to a little above diameter of gear Buy or find a triangular file, file screws to the shape of the teeth, test against a mating gear, you can use marking blue , sharpie or lipstick !! to get a fair mesh. If you want an invisible repair file slightly further and coat with jb weld or similar and file to shape.
It is all a lot of work, but can be done with a pistol drill, drill bits, taps, hardware store screws and triangular files and patience.
Hope this helps someone David Powell.

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Re: Gear Repair.

Post by AllenH59 » Thu May 13, 2021 9:16 am

What I did: I ordered the correct involute cutter from Travers, and waited a few weeks for it to get here, I presume it rested at customs for a while.
I milled out the broken teeth, and brazed up the gear to cut the new teeth in, also filling the teeth to each side of the damaged area. I made and arbor for the gear on my lathe, and turned the brass down until the diameter was correct, and I faced the sides. I put the arbor in my 4 jaw chuck on my rotary table, and centered it and aligned it with the x axis of the mill. My mill is a horiz/vertical.. and I got out the horiz arbor, for the first time ever, I have had the mill about 14 years. I centered the cutter over the arbor, and set the angle on the rotab to zero degrees. I lifted the gear and found the spot to cut by centering the cutter in a groove in an undamaged tooth next to the repair, then i started cutting teeth. The first time I did this, it worked but there was a click in one gear, I looked but could not see what was wrong, I brazed it up again and repeated the process, and the second time it ran silently. Before I ordered the cutter, I got a quote for gear from a custom gear shop in Vancouver BC... They said if I sent them the gear and $875 they would make me a new one, in 6 to 12 weeks. It made the cutter look pretty cheap.

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