# Gear repair fixture !



## Bob Kelly III (Oct 19, 2019)

A friend of mine, Gary Bower  a long time enthusiast of several lathes milling machines and what not. told me how to repair a gear that I have never heard of before
... although brazing up the busted tooth area of a gear is not new, his method for re cutting the tooth area was....
what I knew already was that it takes an indexer to turn the gear so the next slot is in line with the cutter in the milling machine
and rotary indexers like that cost a fortune ....when you can find them and it's hard to justify one for a single gear repair Right?
well Gary told me that he came up with the idea to help his friend about 30 years ago when he had a gear that had busted teeth on his lathe
if you take  a stout piece of flat bar , I used 1.5"x 1/4"x 3" steel scrap I had laying around.  used my Logan lathe to make the pin that the gear will sit on 
 and afixed that to the top right corner of the piece of bar stock when it was laying horizontally in the milling vice.
 and I welded the pin in from the back side .... then ground it flush again.
next i put the gear on the pin and with my awl scribed a arc using the good teeth on the back side of the gear to guide the awl 
I guessed at the horizontal line from where the bad teeth would be re cut to the back side of the gear and scribed a mark then used a center punch and frilled a small hole
( this hole needs to be between the teeth of the gear)  then I found a small nail that fit the hole and cut it off about 1/8" from the top of the gear ....
i welded the nail in place then hand filed the nail to shape ( like a "V" ) and then put the gear back on....  after several tries at fitting it like this I had a very good strong fit
.... I thin found a scrap piece of steel suitable for a  flat bar across the top edge of the bar stock so it would not twist in the vice when putting this thing in and out of the milling vice...  and it was done....
 the idea here is that you have one side that you can squeeze in the vice on the gear and lock it down for the milling.... 
after you set it up and take your first cut and lock the quill down you should be able to take it out and return it to the exact same spot,
once the first tooth is cut you remove the device with the gear intact and ease the gear off and turn it one tooth (to align it up with the cutter on the other side) and put it back in the milling vice and do the next tooth. and repeat till all the teeth are cut anew !
Gary's Idea had a peg that had a tooth on the top to align the teeth to the next step, my version used a nail instead. the disadvantage to the nail is that you must take it out of the vice in order to move it one tooth... with Gary's version you simply loosen the vice, use the peg to align the next tooth and then tighten the clamp again.
there is no doubt in my mind that Gary is one sharp cookie ! 
I call this the "Gear self indexing device" no need for a rotary indexer.... it took me about an hour to make up is all and I did a dry run to make sure I would not run into any limitations when actually doing it..... I saw no problems at all !
.... my only problem is getting the gear brazed up !.... my O/A torch burned up in the ranch fire about 5 years ago and it hasn't been replaced yet !
so I'm on the hunt for a welding shop that can braze that gear now !
.....
 Koodos to Gary ! he saved my bacon on that one ! ..... index the gear with the gear itself ! who'd have thunk it !!!!!!
hahahhah
.....
I think I will add a piece of metal on the end of the thing to make it set in the mill vice the same way each time.... right now it can slide horizontally.... just welding a scrap piece of steel over the corner will stop that from happening  ...it'll be ...put it in the jaws, push down on the top to make sure it's level and push it in till it stops... and tighten it down...... cut the tooth,pull it out advance it a tooth and put it back in...

....
now I can take my time with my lathe indexer and not have to find a 34 tooth saw blade !
his method is far easier !
....
Thanks Gary !
Bob.........


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## Bob Kelly III (Oct 19, 2019)

something that I forgot to mention.... the Peg for the gear to sit in cannot protrude beyond the face of the gear when installed...that very important
if it does, the gear itself won't be clamped tight ( the jaws of the milling vice will hit the peg and not the gear )
......
Bob.


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## HarryJM (Oct 19, 2019)

Hi Bob,

Any chance of posting a picture as this is something that I will be interested in making once I get my shop setup. I did run across a post/picture (and cannot find it now) on Practical Machinist where the author made a self indexing fixture, mounted to a mill table, which looked like a sturdy L bracket that he mounted the gear on vertically with a indexing pin at the bottom.

Thanks,
Harry


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## Bob Kelly III (Oct 20, 2019)

sure !  I didn't spend much time at this, maybe an hour ...and I'm slow in my old age ! LOL
and there may well be a better way to do this sort of thing  but for me this is the cats meow !
if you look real close you can see the nail I used as a pin between the gear's teeth on the back side of the gear
it doesn't hold any pressure it is just there for alignment, the mill vice holds the gear against the flat stock....( to which I added 2 other pieces of steel for alignment purposes)
here's 5 pictures including how I plan to cut the teeth on the 3 in 1
hope this helps !
Bob.........


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## HarryJM (Oct 20, 2019)

Thanks for the pics!


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## Bi11Hudson (Oct 20, 2019)

I have used a similar method in the _distant_ past to repair a small gear. Long before I had a milling machine, or even a lathe. Using just a stick of brass key stock and a file, it is a time consuming but doable process. No welding or brazing, just screwed together. But it worked... and held up for several months while a replacement was located. This before the internet...


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## Bob Kelly III (Oct 20, 2019)

it may well be worth the time to put some greater effort into this, by having a alignment Pin that is bolted to the back ( by counter sunk and flush screws so you can accommodate different size gears to repair... like those of the change gear verity.  you might have to have different Main pins also
to mount the gear on....
the problem comes when the gear is a large diameter  like a bull gear....
it's a thought anyway !
....
Bill, the gear was already repaired by a old method of drilling small holes straight down into the gear and screwing in machine screws, cutting off the heads and then filing the screw shaft into a tooth form.... there is repairs like this on the bull gear on my lathe also 3 screws across the width of the gear.... replacing 1 tooth that had busted off....  evidently some one mistreated the lathe in the past by not stopping the lathe to shift in and out gears.
after seeing the damage done... I stop the machine to shift things..... the split nut and clutch being the only exceptions !
....
I could just add a few more screws in the wide gaps on that small Idler gear....there is room to do that, but I would rather see full teeth across the gear width..... and quiet down the machine a bit when it is engaged and running. i think brass would do that for me !
.....
there is also the dove tail method to hold a piece of metal in the gear,  but that takes an accurate mill and a tiny dovetail on this tiny gear
so that method is usually reserved for large gears...but it works.... too.
.... I am sure variations of these methods would repair most any gear....
.....
....if any of you guys have a different method to repair a gear, no matter how ! I'ed love to hear it !
.....
Gear repair has been something I've been interested in most of my life....and Knowledge is power !

Bob.....


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## savarin (Oct 20, 2019)

tumbler reverse
					

I'm looking into making a tumbler reverse for my 9x20. I'm sort of following the 9x20 LATHE TOP MOUNT REEVERSE TUMBLER by Jeremy Taylor. I'm considering making the shaft for the reverse gear (45t in Jeremy's plans) to fit the 42t gear but making the position adjustable for a 45t when I can find...




					www.hobby-machinist.com
				



post 26
I made this fixture 6 years ago to cut gears successfully so I expect it could cut the repaired gears.
That aluminium gear is still going strong.


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## Bob Kelly III (Oct 21, 2019)

that was quite an undertaking !  but look at the results !  Well done !!!!!!
that is indeed making a gear from scratch ! without using a $900.00 rotary indexer ! FANTASTIC !!!!!
.....and I did bookmark that index printer site...been looking for that for about 5 years now ! HAHAHAHA THANK YOU !
......
I've made 2 aluminum gears so far on the 3 in 1 and they worked very well,..... aluminum stands up really well gear to gear  but for something like I tried to do it was folly from the start ! I made a small gear for a starter pinion on my lawn tractor..... it lasted about 6 to 8 starts and was gone and to make matters worse it took a few teeth out of the flywheel too !
so it is Pull rope time when I want to start that thing now ! Bah !
.....
that gear you made just happens to be the same one I am trying to repair on my Logan lathe the forward /reverse idler gears that engage to the spindle.....and then transmit their power down the chain to the lead screw .
...... after discovering the damage,...... I stop the lathe to mess with that lever !!!!!!
.....
I wonder if anyone has tried to Braze with propane alone ????
I'm going to try it by first firing up the weed burner, and putting it in my small forge, and pre heat the gear and rod it will be on then turn the heat down a bit and then try brazing it with a propane torch.... if it works I'll show ya how I did it LOL.....  
so that is my next project...brazing with propane ! LOL......
later guys !
Bob.........


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## just old al (Oct 21, 2019)

Re: Brazing with propane: Yes, you can. I do it often for fittings and brackets in antique car restoration. Brazing is more than strong enough for things like mounting brackets and the like and I can do it downstairs in the workshop rather than having to run out the car and fire up the MIG or TIG in the garage.

As you say, heat control is important. Do use firebricks to make a muffle to retain heat and preheat on cast iron is always a good idea.


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## Bob Kelly III (Oct 21, 2019)

that's interesting ! because I's seen 5 videos on you tube that say you can't do it ( not enough heat!)
and 3 videos that say you can .... 
any idea what kind of temps your propane torch can reach ? 
it's weird.... as it looks like every propane torch out there burns at a different temp !
LOL....
THANKS for the Response !  it's been about 12 to 15 years sense I've tried to braze anything ! LOL....
Bob....


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## just old al (Oct 21, 2019)

Honestly, they all burn at the same temp - air fuel mix is air fuel mix. Amount of heat on the other hand...there's your magic.

You need to reach temp to melt the bronze and that is the issue. A small, wimpy propane pipe soldering torch isn't going to bring a 30-pouind casting up to temp with any speed - and it'll fail. My present one is a torch and regulator made for plumber's use - runs off a midget propane bottle in its original application but I just use a 20-pounder to run it. I think the brand is a TurboTorch.

I have brazed with a conventional torch on a disposable gas bottle - but careful heat retention is the name of the game,. Firebrick over, under and to the sides to form a pocket to retain the heat helps tremendously.


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## Bob Kelly III (Oct 21, 2019)

ahhh ! thank you for that info  Al !
yah I figured overkill with the heat and heat retention is the only way to go with trying to braze with Propane....
......
ages ago when I had a good Oxy/Acetylene torch i switch from acetylene to propane and actually saw very little difference in cutting 1/4" steel plate
I did have to buy a few tips for the torch though. at $30 bucks a whack !
but the money saved in the long run was in the hundreds of dollars !
.... but when the Ranch fire went through the place all that was left of most of my tools was untempered tools and puddles of aluminum all over the place....Brass did not melt! steel warped cast-iron survived like nothing ever happened !  the cart and bottles we the only thing salvage able.... and I doubt the bottles can be re filled !  the torch though I still have it, has no O rings in it and of course the hose is gone regulators toast and so on....  but I do have a older but still usable 20 gal propane tank and I was thinking of getting a propane torch just for shop use...... or perhaps just use a 5 gal tank I have plenty of those. that happened about 8 or 9 years ago now...but losing 98% of 50 years of accumulation is a hard thing to get over !!! LOL....
.....
just came back in from some lathe work.... "practice threading" and I got a problem with that ! but I'll post it in another thread !
thanks again Al !
Bob.........


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## Downunder Bob (Oct 23, 2019)

Yes as has been said before propane burns in air at a fairly fixed temperature, but will burn quite a bit hotter if used in a torch that you can feed oxygen with. While a propane flame is hot enough you have to have a suitable size burner to provide enough heat, particularly on large jobs and metals that have a high heat conductivity because they soak the heat away from the work area.

Another thing to watch for is not all propane is the same, some some places and brands are mixtures of propane and butane  and even straight butane. Here the main difference is in boiling temps. 100% propane will work much better at low ambient temperatures . Remember also that boiling off the gas will lower the temp of the liquid in the tank so even at moderately low temps your supply of gas may reduce, resulting in lower heat output.


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## Bob Kelly III (Oct 23, 2019)

Interesting ! I thought propane and Butane were the same thing ! Ok very interesting
yah I figured using my 5 gal bottle powered weed burner would make a dandy pre heater ! get that thing as hot as I can with it and then go to town with the hand held propane torch...... I have no idea what the temp is of the little propane torch is but I got it at Squall Mart ( wall mart ) a few years back because it had a self ignition button on it, found it in the camping section ...i'm hoping it will get hot enough , if not I have another older one that is quite a bit bigger and i'll use it ! 
but first I gott'a come up with $20 bucks for brazing Rod !  that stuff has really gone up over the last 30 years  same amount used to be $5.00 !
I haven't brazed anything in AGES !!!!!
Bob.......


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## Downunder Bob (Oct 23, 2019)

The actual flame temp between the various blends of propane and butane are all very similar, it's the size of the flame  size that counts.

And Yes using two or even more torches, if the situation requires it, to preheat, and maintain the large job at a good temp is quite useful.


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## Bob Kelly III (Oct 23, 2019)

Interesting ! because I have seen the cheaper torches  claim max temp of 1700 degrees and others 2800 degrees 
it seams most of the bigger soldering torches do indeed reach  about 2700 to 2800 degrees in temp ( if my memory serves me correctly)
but yet the little torches that run off the same small bottles  struggle to reach those temps. or so they claim !
......
 my bigger torch in the shop is an older one and it has a slow leak around the valve but it is a torch for soldering large copper pipe
it's one of those torches you don't leave the bottle on or it's empty the next time you try to use it ! ...a pain in the arse !
.....i don't hold out much hope for the little auto ignition torch reaching a high temp... as I have used it to try and temper stuff being held in the vice and it is very hard to even get it red hot that way.... ( the vice wicks away the heat too fast) I did get the job done but I had to hold the part with a pare of needle nose vice grips and that held in the vice..... that worked really good )  
this torch is mainly for starting my wood pellet stove.... and it does a great job of that.
.....
years ago with my Hydroxy gas setup, I hooked up a small torch on a hose and melted a spot in a rock ! with a needle size flame !
but that is a different gas all together ! LOL..... ( i used a AC/DC welder on DC to power the 3 cells to get enough gas volume in order to run the torch off the bubbler....  still I popped the safety lid on the bubbler 3 or 4 times when I was farting around with it ! LOL.... the lit flew 250 feet straight up each time ! lol....
.....
I have some oven thermal insulation out there and I will try to make a pocket out of it to hold the gear and short shaft.....
 I have 6 teeth that need repaired ..... that is a big area   almost 1/4 turn on that gear  most of the teeth are just missing pieces but I would like to bring it back up to snuff !

....
Bob......


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## Bi11Hudson (Oct 23, 2019)

There *was* a possibly useful technique some while back for smaller gears that could be cast from aluminium. It involved using Hydrocal, a type of plaster used for molds. The gear was set in a divided form with the good half of the gear being cast. Pins had been set on the dam for later use. 

When the Hydrocal had set, the dam was removed and the gear reversed to expose a usable side with the pins acting to reinforce the joint. Then the other side of the mold was cast. Once that side was cast, the original would be removed and the mold touched up. 

Before use, the plaster mold was preheated to drive out residual moisture and a replacement part cast. Hydrocal will hold up well enough to make two aluminium castings. This I know from experience. It probably would make more before degrading beyond use. 

This tecnique is useful for repairing a gear where gear machining facilities are not available. Hydrocal reproducing the teeth in finest detail. I never tried a large gear but 4" by 1/2" thick worked well. I have heard of it being done with brass, but I'm not *that* good.

.


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## Bob Kelly III (Oct 23, 2019)

that's a cool idea !  i bet if your real careful you get a part that just bolts back in !
I've only done a bit of casting of aluminum,...and I have yet to get the green sand ... I just filled copper pipes and beat the copper till it expanded enough to get the aluminum slug out and used it on the lathe ! LOL.... I did several large round disks that really didn't turn out very well they always had a big dip in the center so I learned to make them 2 times as thick as I needed ! LOL....
I made a forge from a short 2' section of 11" well pipe and made a burner for propane for it and I melted aluminum for a long time with that setup...
what I did was cut a hole about 3" in diam for the heat source to go into...and then used a piece of 6" stove pipe to go in the center of the 11" well pipe and then just made tin flanges for the top and bottom and  filled the gap with Kitty-litter as insulation .... I made my crouseable from a large washer  1/2" thick and a 4" pipe  1/4" wall .....and welded it all up and that worked very good....i use it to this day,  
.....
I've got nothing against aluminum gears , from what I've seen they hold up very well in hard work !
.....
I suppose I could use my bad gear to act as a pattern to cut an aluminum blank into a gear and have a completely new gear !
that would take a completely different fixture to do that but it can be done ! and they're not that hard to make up from the looks of things !
same idea as the other one but 2 gears wide and the nail or Pin is only for the first gear.... 
clamped tight in the milling vice you can copy the original gear quite easily !
I would think that you would need a locating pin between the gears though so they can't turn and get out'a sync !

.....
Bob.....


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## Downunder Bob (Oct 23, 2019)

Repairing a gear without gear cutting equipment. OK making a new gear from scratch is not easy, but repairing an existing one is not too hard. I had an idler gear on a large diesel engine driving a 3 ph alternator, about 1200HP. The cast iron idler gear was the intermediate gear on the timing gears for the camshaft it was a good size about 14" from memory. It was too big for our mill an dwe didn't have any rotary indexing device nor any suitable cutters.

The camshaft had jammed up and the steel driver gear had chewed out about 5 teeth in one spot on the idler. The rest of the gear was good. The process was to fix a sheet of steel shim about 2 or 3 thou, to the gear and carefully scribe the gear profile from a good area covering a few more teeth than the damaged area, also pick up a couple of other spots opposite and at about 90 deg.

carefully cut out the teeth as marked this has to be very accurate. when finished put the pattern aside and prepare the damaged gear for welding or brazing, I chose to braze it as I didn't have any suitable cast iron rods. grind out and prepare the damaged area, then fill it with brazing or welding make sure to overfill all over.

Then set up in lathe . I used a previously prepared mandrel so that I could be sure it was running true. Face both sides leaving 1 or 2 thou. proud and turn the OD again leaving 1 or 2 thou. proud. Paint both side faces with layout blue. 

when dry, afix pattern to one side and scribe tooth profile onto gear, then repeat on other side. Rough out tooth cut out with hacksaw, then file to scribed lines. It's a good idea to test fit into machine before filing too far. At this point you can file the last thou or two from the OD and the sides, and dress up the finished gear to a good fit.

The rebuilt gear was able to run for the next 6 weeks until we got back to home port where a new gear was waiting for us. Examining the repaired gear showed it had stood up fairly well so it was put away in the spares box for that engine.


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## Bob Kelly III (Oct 24, 2019)

Downunder Bob : How long did that process take ? were you guys dead in the water while they were waiting for you to repair it ?
that's a good story Bob.... thank you !  one thing about life, where there is a will there's a way !   
.....
My first runin with cast iron was with a henry ferguson tractor, the starter Snout busted off....so I bought some DC cast iron welding rod and welded it up.... cold.... it busted again  on the second try of the starter........in the meantime I did some reading on the net and discovered that you should heat cast iron before welding it...... so I heated it up with the torch prior to the re weld and then welded it again........ it lasted about a month that time...
I knew that welding causes stress in the parts and it dawned on me that I could weld it till hell freezes over and it would just keep breaking if I didn't relieve that stress after the weld because cast iron is so very brittle.....
so I had a big brush pile burning from land clearing at the time and decided to weld it up again.....  tossed the part in the brush pile and fished it out when it was red hot...... welded it and then tossed it back in the brush pile and added some more brush ... it got very hot...orange even....
i pulled it mostly out of the fire and let it cool real slow... the next day I painted it and put it back in the tractor.... the last I saw  10 years later it was still working.... it hadn't broke again after that !
most people don't know about the stress put into parts if you repair them with welding especially a stick welder ! but it will show up on a cast iron repair if you do not relieve that stress you put into it... and that is done by heating it real Hot cherry Red of better !
.....
Aluminum is much the same way I welded a crack in an aluminum head with aluminum rod.... it re cracked right next to it....
I welded it again and then took the torch and heated it to about 800 degrees it wasn't red hot yet but I could tell it was quite warm.... I tapped the weld seam many times with  a ball peen hammer at that time to help relieve stress caused by the welding and that cured it  knowing those little tricks can sometimes save you from having to do it all over again !
....
Bob....


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## Downunder Bob (Oct 25, 2019)

Thanks for the question, No we were not dead in the water. the ship was powered by a large diesel engine that had a 1.4 Mw alternator driven by  a PTO gear drive and also a steam turbine alternator about the same size. 

The shaft driven set was not able to stand alone as it needed a reference frequency. We could not use the steam turbo set when we were tank washing as we needed all the steam we could get to run the tank washing setup, so we needed the diesel gen set for the reference frequency when tank washing. 

The gear wheel took me just over a day and two of the other engineers repaired the other problems with the diesel gen set. so we had it up and running in two and  a bit days  and were able to continue with our tank washing which we finished with a few days to spare.


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## Bob Kelly III (Oct 25, 2019)

that was a hard repair.. especially just with basic hand tools !  amazing that you got it done , yet alone in 2 days ! LOL......
well done !
...
Bob......


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## Downunder Bob (Oct 25, 2019)

Bob Kelly III said:


> that was a hard repair.. especially just with basic hand tools !  amazing that you got it done , yet alone in 2 days ! LOL......
> well done !
> ...
> Bob......



It's just the life of a marine engineer. we are well trained for these types of situations.


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## Bob Kelly III (Oct 26, 2019)

well, in the continuing saga of the gear repair boon doggel I found something interesting tonight on the lathe....
I mentioned that I had extra gears before that came with the lathe... well in reality I don't have extra gears at all... their the wrong pitch size !
I took the original shift lever out and it's gear assortment on it, including the bad gear.....
and set it next to the one that came with the lathe....  the handle is a smidge shorter but other than that they look the same, upon closer inspection the idler gears are 36 tooth not 34 and the secondary gear is much smaller .... i held the unit in place and it looked fine.... but this time i tried to rotate the spindle and make sure everything was perfect..... it started skipping teeth... I thought "what the heck" and bent down and looked.... couldn't see much in the shadows so I put my glasses on and got my flash light out and looked again the gears on the shifting lever bracket would not mesh with the spindle gear ! .... their just a tad too big....  I thought Damm, all this time messing with those things and their the wrong pitch size ! 
...so back in the box it went and that cured my modifying the indents so the unit would work.... I'm just glad I discovered it before I got the drill over there and drilled the indent holes !  because that was next !
.... so I am back to brazing and repairing the original gear.... I have no other choice now it's that or buy a new one from Logan, at $117.00 a pop...
no doubt as tight as money is around here, ....it's going to be brazing !!!!
HAHAHAHHA
so that is what I did this evening/night..... I am nocturnal by nature so I work at night most of the time !
so I switched tasks and cut 2 -1.5"x 1/4" bars for the bracket that will hold the clicker for the indexing setup....
there is 2 bolt holes on the face of the head stock and I will use them to mount the "L" bracket to hold the things that I decided to put on there
.... on the 3 in 1,...... I made a pair of vice grips , welded a bolt to it and  use it to hold the saw blade when drilling bolt patterns
that worked very good for me and I never had a slipping problem ....not even once <GRIN> 
so I am considering doing the same on the Logan.
......

in trying out my Die holder today with a sharp die..... I discovered a problem....
the lathe stopped..... the belt slipped just when it started to get a good bite.........
which I find odd because I can take .020" cuts with the lathe easy, but it can't handle a 3/8" die ?????   I backed it off by hand and it was hard to do but not that bad !..... 
....
when I first got the lathe it was very DRY so I went over board and oiled everything 3 or 4 times.... now there is oil on the pulleys in the headstock ...I wiped it off with a rag but I don't think that helped much ! 
i need some belt dressing, or rubber cement  that would certainly give the pulleys some grip !
I've contemplated using a can of quickstart to clean the pulleys but that would drip on the back gears below it and I don't want to do that.
..... maybe just running it a while will dry it out more.... i dunno 
i remember soaking a v-belt powered water pump at the ranch when I was a Kid... caught hell for that too !
but I got it working again by cleaning everything with gasoline and then finally taking a bit of sand paper to the running pulleys
soon as I did that it quit slipping..... so I did the belt too ! LOL....
my Dad asked me how I got it working again and I told him he said Boy don't ever put your fingers near those pulleys again ! you could have lost your fingers !  then I explained how I did it.... with a roll of sandpaper between the belts I reached in very carefully and pressed the round bulge of the paper into the v of the pulley  if the paper would have caught on the pulley it would have just ripped it out of my hand....
probably hitting the bottom belt that was heading toward the engine but my arm would not have reached that far !
I had it all figured out,.... but Dad was not happy I took such a risk, 20 miles out in the boonies from the nearest doctor !
 ....ahhh those were the days !
lots of learning went on at that Ranch ! LOL....not all pleasant either !
LOL
later guys !
Bob..........


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## Bob Kelly III (Nov 7, 2019)

Anyway.... I decided to make a aluminum gear blank so I can cut teeth into it with my handy dandy self indexing gear repair fixture !
i found a chunk of 3/4" thick Aluminum (6061T6) that was about 18" long and 3" wide so I cut off a 3" chunk drilled a hole in the center on the flat side and put a bolt through it as an arbor and chucked it up in the lathe.... thinking I would turn it round in no time.... well my depth of cut was limited by the arbor slipping if I went too deep so I kept it at 20 thow for the depth of cut...even through the intermittent part ... turning a square round is a P.I.T.A. !  ....but this even more so as I busted one bolt and had to find another ! .... once it was round I had about 1" of solid metal to trim down
....that took a while ! but this afternoon I finished making the gear blank and decided to test out my idea on the mill....
I cut a trench or tooth valley in the gear blank then put the gear in the fixture.... then cut another one with the pin of the fixture secured in the tooth valley on the back side.... .....
 HOWEVER..... I neglected to mark and measure where each tooth should be and that new trench is probably in the wrong spot ! I'ed almost bet on it !
 as I didn't adjust the height of the quill on the mill at all..... so all that work making the blank was just good practice I guess !
 tomorrow I will see if the gear blank can be saved ....if not I'll just have to make another one !
and I discovered that my tooth profile on the milling fly cutter ain't so great it's leaning more to one side than the other !
.....I know I will have to repossion the spindle height in order to pull this off but the question is do I cut below the tooth slot or above it ?
and sense the teeth centers are something like 70 thousandths apart there is no room for error !...and I don't do very good on super pression stuff
.... I may pull the blank and scribe a line to the center for each tooth but that is prone to error too !  but it would give me a better idea of what I am dealing with ....
I am trying to index a gear by itself while making it.... to my knowledge that's never been done before
I can already see the need for a revised self indexing gear fixture....one with an adjustable pin that can go up or down at least 1/4" 
that would cure having to reset the mill Quill......
oh well.... time will tell if I can do it or not LOL.....
later all !
Bob.........


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