gear hobbing /spline cutting ? school me - Page 2
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  1. #21
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    Matt,
    I just got the identical machine about two months ago. Although mine was not as nice looking as yours, I know a little about your situation right now. You are really lucky to get so many gears with it. Did you get any extra spindles ort the manual? It's not essential but it is pretty helpful. Contact me off line if you have any questions, I'd be glad to share what I have learned so far.

    Rick

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    Kearney is about 50 miles from where I grew up. It used to be Kearney State Teachers College. At one time, they had an industrial arts teaching program. That's probably all it got used for. When they joined the University of Nebraska system about 15 years ago, a lot of that equipment was sold on auction. I would almost bet its been sitting that long.
    JR

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    Here's a little update & photo essay on the hobbing project.

    A couple problems with the machine to sort out. Most serious is that the work arbor is *stuck*. I mean really stuck. I went as hard as I could stand with a 4lb hammer driving a bronze rod and didn't get it to release. Then I wanted to take the spindle bearing out of the equation and just press only on the spindle tube.

    So...the headstock had to be removed. My trusty little orange as a "skyhook" and a come-along for careful positioning to keep the driveshaft and ways parallel as I extracted the headstock. Believe it or not, this machine is 75% of a miniature horizontal boring mill !!! (If making your own lathes get too tiresome ).



    Then the headstock went into my 12 ton arbor press. I bent the bronze rod into a pretzel as it wasn't a tight fit in the bore, and finally converted over to a steel rod with a close fitting steel pilot attached. Nothing going on even with me hanging on the 4 foot press-lever-arm.

    Sooo....first I set up C-clamps and web straps to secure the headstock. I got out a step stool and "sat" on the press-arm, wielding an 8lb sledge hammer in my hands, I struck a fearsome blow to the top of the press ram under heavy down-pressure. CLANG and the arbor was out...no damage to anything whatsoever (not even the paint can that I feared I would puncture and moved it beforehand )



    Alas, someone had gotten overzealous with the index banjo and cracked off one of the clamping ears. I debated making a brand new duplicate from steel, but decided I better try to fix the old one first. I drew out a little sketch on the side of the part where I had a 1/4-20 socket head screw "buried" in the part...and with a little creative setup on the mill, got it right where it counted. A little metal was lost in the process but not where the strength is really required in the part. Also counting my lucky stars for that 3/8" solid carbide super long endmill that just happened to be in the drawer.




  5. #24
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    Time to make some gear blanks!

    Square CRS flat stock, cut with cold saw, bore and face one side. Saw the corners off on the bandsaw to reduce interrupted cut somewhat, turn over, machine OD and the other face.







    Work in progress. Mobil Omega (dark oil) in use. The mechanical coolant pump doesn't work for some reason and I had already filled the tank I stole the peristaltic pump from my horizontal mill which had never seen action and it is working just fine.


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    Finally, I can relax. These are 27T, 16DP gears just for a test.



    They look pretty good except for one tooth flank all the way around has some gouges in it...I think I have too much play in the hob's arbor and it is inducing a little chatter. Opposite tooth flank looks good all the way around. You wouldn't know about the problem by rolling them together...very smooth.

    More to come.

    -Matt

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    Looks good, Matt. Is it all right if I'm a little bit green with envy? [img]smile.gif[/img]

  8. #27
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    Good job Matt. That's a pretty hefty DP for a hob that is supported on only one end. You might not have any problems with smaller DPs. Now that you have the first ones done it just gets easier.

    Rick

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    matt,
    i always put an internal keyway on my blanks first.a 1/8 will do.to keep the blank from spinning on the arbor.then later you can always punch the keyway to size.

  10. #29
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    You know Fix, I had strongly considered that, except there is no keyway on the work arbor I got.

    But after more consideration, the cutting forces on the gear blanks are almost perfectly parallel with the spindle axis, and the other gear recesses in the cut help to keep it all timed.

    Granted, I was sweating a little bit during the first run, thinking if a blank slipped badly or the index gears came out of mesh it could cause a nasty crash.

    -Matt

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    Default Spline problem

    Hi.Im new and need some help.Im running a BC1636 and doing some splines on a shaft.It starts out ok ,then it starts pulling left when you engage the feed.It pulls left over 3 inches about 1/4 inch.
    Attached Thumbnails Attached Thumbnails 20191202_145809.jpg  

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    Quote Originally Posted by Ralph51 View Post
    Hi.Im new and need some help.Im running a BC1636 and doing some splines on a shaft.It starts out ok ,then it starts pulling left when you engage the feed.It pulls left over 3 inches about 1/4 inch.
    Parts are moving or your index gearing is wrong. Last possibility, you've got a differential and it isn't locked out.

    Splash some bluing on where the part is held and scribe a line, if that moves under cutting forces, there's your problem.

    Very unlikely but you do have the hob slide clamped ?

    Your machine appears to be upside-down, by the way. The oil stays in better if you mount it on the floor ... which reminds me. Umm, where the hell is the cuttin' erl ? Should be a ton of it splashing around on your hob/part interface. I dont see no evidence of ANY.

    And don't even think of using water-soluble. That ruins gear machines.

  13. #32
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    Default BC 16-36 1951 model

    Good morning,
    Thank you for your help.I have been working on this machine and im not a machinest by all means.My first project was this 1951 BC 16-36 horizontal hobber.Someone wired it 480 and forgot to change the coils in the differential to 3 phase 440.The original two blew when they powered up 3 years ago.Just some history.I got a book that pretty much explained how and what to chevk and do.Come to find out the manual is missing pages.7,8and. 9.This explained how to set the differential and tje timing tabs that contact the 4 positioned micro switches.I havent a clue on this part and how its set up.Now the spindle has a 31/2 inch hole.Its new.The ho is used and is set to cut 9 splines.The spindle is correct as it turns one revolution and hobb 9 turns.The witness marks are exact on the shaft on one end.Then jog toward spindle side and touch hob and its exactly parallel with tje first touch.Now I backed the hobb backward to the start and reblue and touch.Perfevt.Its when I press feed and it starts feeding it curves to the left 1/4 inch on all splines.The index called for on the cover 80 driven and 34 driver i think.I put what the chart said on cover for a 9 tooth.The index is correct.The feed was 0.150 and on the differential gear side I put 72 driven and 34 driver just for test.I have changed the gears on the feed at least 20 times differt ratiod.and the differential 10 times.The surface speed gears are not spur and they are helical.I never changed them.Something like. a 21 on bottom and 72 on top.We have put a dial guage on the spindle and its within .005.All the way around.The shaft is good to.This machince is really nice.It has a single lead screw and now a new coolant pump and is wired 480volt three phase.It has about 20 gears from 27 tooth to 99 tooth all spur and new.The hob is for cutting 9 splines at 2 degrees 47 minutes.30 degree PA.The it say Something on side like 30/60 DNP.I get the specific on that at work this morning wjen I try what you mentioned.My boss has been in business 40 years and never seen this problem before without fixing it.Everyone at work is clueless.I called adamsmachine and talked to one guy.He didnt even know or wanted to guess.I love this machine.Its an automatic.I am looking to find how to set it up as well.Its has a new oiler on the front and electricail with a timer.i will get more pictures.Thank you so very much for your help.

  14. #33
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    Quote Originally Posted by Ralph51 View Post
    I got a book that pretty much explained how and what to chevk and do.Come to find out the manual is missing pages.7,8and. 9.This explained how to set the differential and tje timing tabs that contact the 4 positioned micro switches.

    The spindle is correct as it turns one revolution and hobb 9 turns.The witness marks are exact on the shaft on one end.Then jog toward spindle side and touch hob and its exactly parallel with tje first touch.Now I backed the hobb backward to the start and reblue and touch.Perfevt.Its when I press feed and it starts feeding it curves to the left 1/4 inch on all splines.The index called for on the cover 80 driven and 34 driver i think.I put what the chart said on cover for a 9 tooth.The index is correct.The feed was 0.150 and on the differential gear side I put 72 driven and 34 driver just for test.I have changed the gears on the feed at least 20 times differt ratiod.and the differential 10 times.The surface speed gears are not spur and they are helical.I never changed them.Something like.
    Okay, first thing I think you need is a manual that's not missing pages

    Most Barber-Colmans do not have a differential. Let me try to explain ...

    Basic gearing lesson for mechanical hobbers :

    Speed gears - they set the speed that the hob rotates at. This determines your cutting speed. Since the work is geared to the hob, it also determines the speed of the work but that doesn't matter. It's the speed at the cutter that counts. You choose these according to the material and the diameter of the hob, just like for milling cutters.

    Index gears - these determine how many teeth you get in the part. For example, if you want ten teeth, the index gears make the hob rotate ten times for each rotation of the work. One time for each tooth.

    Then the feed gears - those determine how fast the hob feeds along the axis of the part. With spur gears you can use anything you want and the index will stay fine. It is separate. A good number for starting out is about .030 - .045" on an average type gear. Less for small teeth, more for big ones. There's a chart for choosing them.

    That's all for spur gears. IF you have a differential, then THAT makes the helical angle of the teeth. You have to calculate which gear ratio will give you what helix angle.

    If you are cutting spur gears, the diff should be LOCKED OUT. Otherwise it will cut a helix, which you don't want on a spur gear. There will be a lever or a knob somewhere.

    Without photos it's hard to tell because a beginner's descriptions are not always exact but this sounds like your problem.

    It is also possible to cut helicals on a machine without a diff by coordinating the index and feed gears, but that's a second semester lesson.

    Round yourself up a manual that is not missing several pages, that'll be a big help

    Good luck and report back, please.

  15. #34
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    Mr Goldstein,
    I havent been back to the shop today,but you just found my problem.I know for a fact its the differential because it is kicked in and has been.Im calling my boss now and having someone kick them out.(the diff).thank you so much.Iwill keep you posted.Ill be there tomorrow to see it.Thank you again.
    Sincerely
    Ralph


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