# Involute gear cutter type for carriage travese gear please



## Dranreb (Feb 22, 2014)

Hi folks, I've had limited success broaching these two gears, it was an interesting exercise but I think the time has come to make a proper job of it!

I'm thinking someone here must have made some, so to save me a lot of head ache work, does anyone know what type/size of involute gear cutters I need to order to cut the two apron traverse gears please?

old gears




new broached gear




Bernard


----------



## benmychree (Feb 22, 2014)

You could probably take it to a bearing house that may have gear gages to determine the pitch and pressure angle, otherwise consult a machinist's handbook and count the number of teeth and pitch diameter, from that you can determine the diametral pitch and all the dimensions should fall into place; without knowing where it was built, one cannot assume it to be diametral pitch, it may be metric (module), depending where it was built.  By the looks of it, I'd say it looks to be 
14 1/2 deg pressure angle, not 20 degree, but without straight on pictures, that is a guess.


----------



## pdentrem (Feb 22, 2014)

Do I assume that this is off one of the Atlas lathes? If so, not module, just standard. Download Boston Gears chart 

http://www.altraliterature.com/pdfs/Spur Gears 17-62.pdf

or use Machinery's Handbook gear charts to identify the gear.
Pierre


----------



## Dranreb (Feb 23, 2014)

Thanks Pierre, I've been looking for something like that for ages!

Sorry, I should have mentioned it's for an Atlas..

Bernard


----------



## docn8as (Feb 27, 2014)

number of teeth +2 /O.D.= P.              For just a  couple  gears  , grind the  tool bit  from a  lathe  bit  to fit  a good  section of  the  broken gear & save  yourself  abt $75+ dollars  .. IT  WORKS  WELL 
best wishes 
doc 

#8 cutter  - 12-13 T of  
     #7 for 14-16
      #6 for 17-21
    #5 for 22-25
$4 for26-34
  #3 35 54
  #2 55- forgotten 
   #1  rack


----------



## rgray (Feb 27, 2014)

docn8as said:


> number of teeth +2 /O.D.= P              fo rjust a  couple  gears  , grind the  tool bit  form a  lathe  bit  to fit  a good  section of  the  broken gear &save  yourself  abt $75+ dolLARS  .. IT  WORKS  WELL
> best wishes
> doc
> 
> ...



#2 55-134
#1 135-rack

My info says #6 17-20
                 #5  21-25


----------



## docn8as (Feb 28, 2014)

yes ...i havent  checked a text  ,but  pretty  sure your numbers  are  correct & mine  are  in  error.....chalk it up to an 82  yr  old  memory ...
  FWIW..... for  those may  be  obsessing abt  cutting gears "by the  book",.......particularly with  adjustable meshing , things  are  not  so  critical ......i have  been  using a  24 tooth stud  gear on my 1895 Reed  14 in lathe that  i  cut   w/ a # 6 cutter which  was  what i  had on  hand .....no problem  in 12  years  now.........when i cut the gear  for  my  Barnes  4 1/2 thread  dial that  i made , i calculated  i needed near a 32 pitch gear ( EXACT pitch  not  necessary  & near impossible to  cut in  home  shop.....,it  just  needs to roll in mesh  .slack being  taken  up ..even  xact  FORM not  necessary )   .....i happened to  have a  30 pitch  cutter , & cut a slightly  smaller  gear  blank  than  "spec" ,.... the  larger spaces  & thinner teeth  allowed a nice  easy  rolling  action....have not cut any thrds  on it yet  , but  test  cuts  have  been  just  fine ...no cross threading  on successive  cuts ....
    i have  seen a  statement in a  "Brit "  book  that  due to  cost , many  just  cut  all change gears  w/ a mid size  cutter  & ran them in w/ abrasive .....kinda  xtreme & unnecessary  since lathe bits  carefully  ground  to fit a  gear  used as a  gauge , work quite  well ..i used one of  these on my  monarch  A thread  dial that  i  made .(  used the 12 pitch lead screw  gear as a gauge ,  ...4 Pitch lead  screw)......
     best  wishes
doc


----------



## iron man (Feb 28, 2014)

I dont know but the gear you made looks pretty good it is such a slow turning gear I dont think you would have much problem with the one you made if I had that gear laying around in my shop I would use it, I need to cut one for mine as well I just have not got around to it. Ray


----------



## jererp (Mar 1, 2014)

An easy way to check the pressure angle of a gear is to roll it in some modeling clay. That will generate a tooth form with straight sides. Then just measure the angle of the tooth formed in the clay.


----------



## rgray (Mar 1, 2014)

docn8as said:


> yes ...i havent  checked a text  ,but  pretty  sure your numbers  are  correct & mine  are  in  error.....chalk it up to an 82  yr  old  memory ...best  wishes
> doc




Pretty amazing to have all that in memory. I have a cheat sheet on my desk is the only reason I had the info. I buy a cutter or two on ebay when I find a good price and my cheat sheet is how I keep track of what I have so I don't by duplicats.


----------



## Jimmy (Mar 4, 2014)

The gear you made looks great to me.  If I could do that good I wouldn't be trying to get the local gear shop to make one for me.  I need the gear that goes on the cross feed screw.  When I bought my lathe it was gone, along with the cross feed dial and pinion.  I've been trying to make all of this but I thought I could probably purchase the little gear easier than I could make one.  However, now that I have been quoted $275 for the little 17 tooth gear, I may need to re-think.  How did you make the one you have?

Jimmy


----------



## wa5cab (Mar 5, 2014)

Jimmy,

You didn't mention what size your lathe is (10" or 12") or what vintage or better, model number.   But you can probably buy a new gear from Clausing.   It probably won't be cheap but it is certain to cost less that what a job shop would charge for making just one.  Another source is of course eBay.  And a third is some member of this list or of the appropriate Group or Groups on Yahoo.

Robert D.


----------



## jererp (Mar 5, 2014)

It seems like you could match it up to a std. from someone like Boston Gear, and make some alterations as required for a lot less.


----------



## Jimmy (Mar 5, 2014)

wa5cab said:


> Jimmy,
> 
> You didn't mention what size your lathe is (10" or 12") or what vintage or better, model number. But you can probably buy a new gear from Clausing. It probably won't be cheap but it is certain to cost less that what a job shop would charge for making just one. Another source is of course eBay. And a third is some member of this list or of the appropriate Group or Groups on Yahoo.
> 
> Robert D.



I bought a Sharp 1882S from a scrap yard.  It had been turned over on it's face and all the controls broken off and missing.  I could hardly believe the condition it was in because it has hardly been used.  However, after trying to work with Sharp for the last five months, I now understand why it was scraped.  Sharp will not even talk to me about getting parts for it because it is "obsolete", even though it is a 1999 model.  I even tried to buy parts for a similar machine that they are currently selling - after two months on a "ten day lead time" I gave up on that also.

I went to a dealer in Houston who deals with Sharp on a daily basis, fuguring that they would get better results than I.  No luck!  They were not any more helpful to the dealer than they were to me.

I have tried Boston Gear and Martin Sprocket and all the others I could find online.  Nothing close to what I have calculated the gear to be.  I even ordered the gear from a local bearing house, after being told by the local gear shop that it was the correct gear for the lathe.  Not even close and $47 for a $12 dollar gear.  I took the specs to the local gear shop after making all the computations myself and was quoted the $185 price because he does not have the cutter and would have to rent one.  OK, after all I have spent on this boat anchor, what's another $185. But the guy won't call me back.  I assume he does not want to mess with it, and I understand that.  I was in business for over 30 years and understand that some jobs are just not worth the time.

So, now I'm down to making it myself.  After all, this is just a hobby and I have already learned a lot about gears.  However, some input from someone who has done it before is always helpful.  

P.S.  I would not recommend anyone buy a Sharp lathe.  They are good looking machines, made in Taiwan, but NO service after the sale by the U.S. distributor.


----------



## iron man (Mar 5, 2014)

I need to cut one for mine I suppose I could be talked into cutting another 1/2 of material for one. Ray


----------



## Dranreb (Mar 6, 2014)

Thanks for all those replies chaps, just got back from a break in Dubai, will get back when recovered....
	

		
			
		

		
	






	

		
			
		

		
	
:thumbzup:


----------



## Dranreb (Mar 6, 2014)

docn8as said:


> FWIW..... for  those may  be  obsessing abt  cutting gears "by the  book",.......particularly with  adjustable meshing , things  are  not  so  critical ......i have  been  using a  24 tooth stud  gear on my 1895 Reed  14 in lathe that  i  cut   w/ a # 6 cutter which  was  what i  had on  hand .....no problem  in 12  years  now.........when i cut the gear  for  my  Barnes  4 1/2 thread  dial that  i made , i calculated  i needed near a 32 pitch gear ( EXACT pitch  not  necessary  & near impossible to  cut in  home  shop.....,it  just  needs to roll in mesh  .slack being  taken  up ..even  xact  FORM not  necessary )   .....i happened to  have a  30 pitch  cutter , & cut a slightly  smaller  gear  blank  than  "spec" ,.... the  larger spaces  & thinner teeth  allowed a nice  easy  rolling  action....
> 
> lathe bits  carefully  ground  to fit a  gear  used as a  gauge , work quite  well ..
> 
> doc



Thanks for the confirmation Doc, when I started this project those where almost my exact thoughts, slow speed and adjustment made it easy, and I made two cutters, one each for the small and larger gear.

I broached a couple of very good practice gears in ally, cut off tool, then form tool, took around 1/2 hr to do .







Then I made the one shown before in free cutting steel which engages the rack and it works very well, here with the shaft relieved to clear the lead screw, this one's a keeper.




The larger gear for the other end of that shaft suffered when the indexing pin worked out of the bull gear and I didn't notice and spoiled a couple of teeth, a bit disheartening as it was the last few teeth..the whole gear train when assembled works OK but the couple of bad teeth and the skinny teeth mesh rather sloppy and make an intermittent roughness I don't like..




The other shaft/gear on the left for the  apron crank handle) looks good  but teeth are too skinny which makes them klonk when in use.






iron man said:


> I dont know but the gear you made looks pretty good it is such a slow turning gear I dont think you would have much problem with the one you made if I had that gear laying around in my shop I would use it, I need to cut one for mine as well I just have not got around to it. Ray



Ray that one is OK but all subsequent ones had faults I wasn't happy with.



jererp said:


> An easy way to check the pressure angle of a gear is to roll it in some modeling clay. That will generate a tooth form with straight sides. Then just measure the angle of the tooth formed in the clay.



Another good tip jererp, we badly need this sort of info!



Jimmy said:


> The gear you made looks great to me.  If I could do that good I wouldn't be trying to get the local gear shop to make one for me.  I need the gear that goes on the cross feed screw.  When I bought my lathe it was gone, along with the cross feed dial and pinion.  I've been trying to make all of this but I thought I could probably purchase the little gear easier than I could make one.  However, now that I have been quoted $275 for the little 17 tooth gear, I may need to re-think.  How did you make the one you have? Jimmy



I used my lever operated compound Jimmy ...http://www.hobby-machinist.com/showthread.php?t=19267

The problem with broaching gears in steel is that the cutting edge of the cutter in contact with the work increases as it goes deeper, this really finds any looseness in the gibs/lead screws/indexer/chuck drive pin etc. Even with all gibs locked this can cause chatter which can alter the indexing if care is not taken, once the chatter marks are there it's almost impossible to cut that gear smooth again before cutting too deep.

I could use the tools I made in a flycutter but that really gives the bull gear drive pin a workout, don't want it to get worn out! For that reason I'm thinking of using a involute cutter unless you guys have a better idea.........One of my self imposed disciplines is to make everything as near to free as humanly possible, so far I have spent almost a couple of quid on this..

Bernard


----------



## rgray (Mar 7, 2014)

Jimmy said:


> I bought a Sharp 1882S from a scrap yard.  It had been turned over on it's face and all the controls broken off and missing.  I could hardly believe the condition it was in because it has hardly been used.  However, after trying to work with Sharp for the last five months, I now understand why it was scraped.  Sharp will not even talk to me about getting parts for it because it is "obsolete", even though it is a 1999 model.  I even tried to buy parts for a similar machine that they are currently selling - after two months on a "ten day lead time" I gave up on that also.
> 
> I went to a dealer in Houston who deals with Sharp on a daily basis, fuguring that they would get better results than I.  No luck!  They were not any more helpful to the dealer than they were to me.
> 
> ...




I have this . Private message also sent.


----------

