# Gears for the non machinist



## bcall2043 (Jun 18, 2012)

jumps4 said:


> gears for the non machinist is a thread i can do and i have been thinking about doing. since i feel i can do it here without being made fun of by the real machinists with the equipment. you would be amazed what someone like me without formal training and no funds for gear cutter sets can do at low cost. i now can match a gear perfectly with free software and make the cutter then the gear and cut it in steel brass or aluminum with a shop made cutter. the cnc lathe turns the involute and the 4 axis mill makes it a cutter, heat treat setup a grinder in the mill and grind then setup the 4 axis mill cut the gear all cnc except stoning the edges. my latest project is a model of an old mill and i wanted to match the number of teeth on each gear to the original mill. 100 teeth on a 12' gear meant 100 teeth on a 12" gear and the other drive gears match the original
> steve



jumps4

I did not want to take your original post more off topic but I want to say I like your idea for a make-your-own gear thread for us non machinists. I bet some of the Hobby-Machinist members have tools with broken or missing gears. Others may want to make something with gears and make the gears as part of those projects. I know I have an old lathe with a broken gear that will need to be repaired or replaced before I can get it working. I have not decided if I will try to repair the broken teeth, rework a new stock gear, or make a new one from scratch. I know buying one from the lathe vendor would be too costly if they have one. 

Looking forward to the new topic. I'm sure others are also.

Benny


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## jumps4 (Jun 19, 2012)

hi benny
well lets try this I hope i can make it clear enough and still keep up with the other thread
first i need to ask if you have a cnc lathe and cnc mill 4 axis if not this is going to be fun but still possible.
so what tools are we starting with?
I also would like to know the diameter of the broken gear and the number of teeth
steve


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## jumps4 (Jun 19, 2012)

and a pic of your old lathes gearing would help and a list of other gears (just # of teeth) that fit the lathe you may have. does the lathe have another gear the same size on it or maybe one that twice the teeth.
there are a lot of ways to do this is why i ask and your tools and other parts help decide the way we will go at it.
steve


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## JohnAspinall (Jun 19, 2012)

On the general topic of wrapping your head around all the terminology associated with gears:
the animation on this Wikipedia page: http://en.wikipedia.org/wiki/Involute_gear
is worth more than 1000 words in understanding "pressure angle".


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## jumps4 (Jun 19, 2012)

thanks john
that will help to show the shape of the gear tooth cutters profile and why it  is that shape
hopefully benny has a cnc lathe  and a piece of tool steel this will be easy
if not, patience will turn  the cutter profile and he owns the test gauge already
steve


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## Philco (Jun 19, 2012)

Benny, I had a gear on my on my early 50"s model clausing lathe to strip out a section of gear teeth caused by my on carelessness "stupidity"about 15 years ago.this gear controlled the cross slide & without it I was stuck. I got a hold of a clausing service center that had the gear for around $250.00 plus shipping. I paid my STUPID TAX, put the gear on & everything was fine until my stupidity kicked in about 5 years later when I DIDN"T release the cross slide &stripped out the same gear again. I immediatlely knew what I had done. That sick feeling came over my whole body. That sick feeling quickly  became a" I"M GOING TO THROW UP NOW feeling right after I called the clausing service center & that same gear was now like $600.00. A good friend of mine that worked in a local machine shop  looked at it & said he could fix it. He cut out the damaged section and brazed in a new section, set it up in a grinding fixture, indexed off of a good section of teeth & then ground the new teeth. Installed the gear & eveything was fine for a few years until I had to leave the transmission shop for about a week. The very morning that I got back to the shop, one of the guys that worked for me that liked to "play on the lathe " came up to me with "some bad news". He stipped the gear out again. I let the lathe set for about 3 or 4 months while I decided whether to fix it again  or buy another lathe. My friend that worked at the machine shop had taken another job & was no longer  available to help me. I finally talked to another machine shop  about fixing the gear & the cost involved. He gave me the name of a place in North Coralina that made gears. I called them up, sent them the gear for an estimate. The gear was going to be about $50.00 plus shipping. I couldn"t believe it. I asked them if they could make me two gears while they had it set up. I still have the 2nd gear in my tool box just waiting for another "STUPID MOMENT".        
The name of the company is:
SPENCER-PETTUS     
1312 Ramseur Rd.
Bessemer City
I hope this information will help someone now or in the future.
Phil


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## Charley Davidson (Jun 19, 2012)

Benny doesn't have any CNC equipment but he has several indexing heads and rotary tables along with every shape of gear cutter known to man. Oh and 2 horizontal mills, 2 lathes (3 I gave him a Craftsman) & a vertical mill


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## jumps4 (Jun 19, 2012)

ah ha i thought he didnt know how...
tricky benny    lol
is he ok i havent seen him since his post charley
steve


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## Charley Davidson (Jun 19, 2012)

Talked to him today, he posted in another thread today trying to save his rotary table from doom :lmao:


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## jumps4 (Jun 19, 2012)

ok i pmed him thanks charley
steve


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## bcall2043 (Jun 20, 2012)

jumps4 said:


> ah ha i thought he didnt know how...
> tricky benny lol
> is he ok i havent seen him since his post charley
> steve



Steve,
Sorry so late getting back to this post. I somehow missed it earlier.

Never said I didn't know how gears are made, I can read a little.:lmao: However I am not a machinist and have never repaired or made a gear. I thought we might all learn from how you would do it.

Charley is correct I have a few tools. All are very old manuals with no electronics. The most complete index head I have is a very old one with the slotted wings like shown in the early Brown and Sharpe catalogs. I have misc. index plates with only one that fits the head. The other head is a very large one too big to fit on anything I have. The lathe with the broken gear is a single tumbler Southbend 14 1/2 inch swing and is a future project that will hopefully replace the smaller lathe I now use. I will try and get more info on the broken gear and lathe gearing. As Charley can verify, the lathe is buried right now and I just parked another bandsaw (read project) in the way.

Thanks, 
Benny


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## bcall2043 (Jun 20, 2012)

Philco said:


> Benny, I had a gear on my on my early 50"s model clausing lathe to strip out a section of gear teeth ............... I finally talked to another machine shop about fixing the gear & the cost involved. He gave me the name of a place in North Coralina that made gears. I called them up, sent them the gear for an estimate. The gear was going to be about $50.00 plus shipping.................
> The name of the company is:
> SPENCER-PETTUS
> 1312 Ramseur Rd.
> ...



Phil,
How long ago was that price? That is cheaper than the cost of a new involute gear cutter.

Thanks, 
Benny


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## jumps4 (Jun 20, 2012)

lets make the gear without an index head or a rotory table just your old gear and some jigs when you get cleaned up enough to work in the shop. it will make a good thread. 
what is the old gear made of? and these are straight teeth right?
steve


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## Philco (Jun 21, 2012)

bcall2043 said:


> Phil,
> How long ago was that price? That is cheaper than the cost of a new involute gear cutter.
> 
> Thanks,
> Benny



Benny, I had Tammy pull up the invoice on the gear purchase from SPENCER- PETTUS & it was in 2004.
The phone # is 704-629-4327
 The address is 
1312 Ramseur Rd.
Bessemer City
North Carolina 28016
The gentle man that I talked to was Mr. Joe Brown

Phil


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## core-oil (Jun 21, 2012)

This somewhat rough &ready repair which i carried out approximately 30 years ago, may be of some help to the members

   A neighbour of mine had an old Skoda motor car at that period in time, In those days they were considered absolute crap!   Nowadays they are excellent machines, however this is the scenario, He was going on holiday & burst three teeth out of the starter ring in the flywheel Needless to say the local dealer could not help him in time Before he was due to go away,

   We took the broken ring off the wheel, And i machined a dovetail section over the space of the broken teeth area,  & fitted in tight a steel matching dovetail, leaving enough metal over the top of the teeth  This was all done on a little 6" travelling head shaper  Fortunately there was enough thickness on the ring that taking out &fitting in the "splice" did not weaken it too much
  I then cut a portion of tinplate, coated it with layout fluid, &  made it the profile of the ring outside &inside dia, Then with a fine sharp scriber marked the tooth profiles &filed them out

 Placing the ring once again in the shaper vice, To make matters worse, the teeth were set at 30degrees angle, so i set the machine vice round as appropriate

   Next i filed &hardened a pice of high carbon steel, &proceeded to shape out the tooth profiles , Not the ring was "looped around the machine table" , By gently &carefully moving the ring around to the desired point required machining the tooth profiles was not too bad,  This plannig out was done to marking lines from the template, somewhat carefully   After machining out  I finished the teeth flanks with a file. Fitted the ring back on to the flywheel  & screwed down a small high tensile screw in the middle of one of the flank bottoms really tight, blued the starter motor pinion &checked the fit from it
&filed & scraped a couple of high spots  The emergency repair lasted another five years ! 

  boxed it all up, The emergency "one week repair lasted another six years!


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