Page 1 of 7 123456 ... LastLast
Results 1 to 15 of 91
  1. #1
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    68
    Posts
    5,634

    Default 0.3 Module Gear Cutting Query

    I need to make a replacement fine focus gear for an early '70s Nikon S microscope. The original gear is nylon with a brass hub and it is commonplace for the nylon to split which is what has happened to mine. Spares are no longer available.

    The gear has 107 teeth, a pitch diameter of 32.10mm and a 20 degree pressure angle. I have not removed the gear from the scope but photos of others online would suggest a thickness of about 5mm.

    I have looked online for cutters and while there are some in the Ukraine, something closer to home or possibly even home made has more appeal.

    Would a single point fly cutter be up to the task? Whether I'm up to the task of grinding the cutter is something else.

    BT

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Age
    2010
    Posts
    Many





     
  3. #2
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    50
    Posts
    1,938

    Default

    You could certainly use a fly cutter to do it, but as you mentioned you would have a hell of a time grinding the profile.

    Maybe you could use a magnifying glass when grinding the profile?

    Can you buy a similar gear? Wouldn't matter if it was thicker or had a different hub.
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  4. #3
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    7,775

    Default

    That's what optical comparators are for Bob!
    If you wait long enough I'll grind you one on the Wickman..... I doubt you'll want to wait THAT long lol

    You dont say what you'll be making the replacement out of, though for a one off, I doubt it would matter.

    Stuart

  5. #4
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    68
    Posts
    5,634

    Default

    Vernon,

    Seeing what I'm grinding wouldn't really be an issue, it would be an ideal opportunity to use one of my stereo scopes. As far as buying an over the counter gear that matches the original goes, any suggestions? I looked at HPC Gears and they offer a 108 tooth gear. Close.


    And Stu, yes the comparator might prove real handy. The gear would be brass.

    BT

  6. #5
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    50
    Posts
    1,938

    Default

    Yeah I did have a look for a stock gear, but could only find this anti-backlash gear - http://www.reliance.co.uk/shop/produ...ath=32_355_362

    EDIT - here is one from the same mob - http://www.reliance.co.uk/shop/products.php?17530
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  7. #6
    Join Date
    Oct 2011
    Location
    Adelaide
    Age
    56
    Posts
    3,149

    Default

    I'm sorry to say that I can't help you there Bob as my smallest cutter is M0.5.
    This article explains how to make a form cutter -
    http://www.metalwebnews.com/howto/gear/gear1.html
    Which I think is probably less stressful than trying to grind a fly cutter symmetrically.
    However, your depth of cut is only 0.65mm - not very big!
    Your last problem is the number of divisions. 107 is not in the common ratios for dividing heads or rotary tables. Do you have the set up for differential indexing?

    Michael

  8. #7
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    66
    Posts
    1,417

    Default

    Quote Originally Posted by Anorak Bob View Post
    I need to make a replacement fine focus gear for an early '70s Nikon S microscope. The original gear is nylon with a brass hub and it is commonplace for the nylon to split which is what has happened to mine. Spares are no longer available.

    The gear has 107 teeth, a pitch diameter of 32.10mm and a 20 degree pressure angle. I have not removed the gear from the scope but photos of others online would suggest a thickness of about 5mm.

    I have looked online for cutters and while there are some in the Ukraine, something closer to home or possibly even home made has more appeal.

    Would a single point fly cutter be up to the task? Whether I'm up to the task of grinding the cutter is something else.

    BT
    Bob, here is a set of 8 M0.3 involute Module gear cutters from Belarus - US$80 is quite a bargain, less than $9 each and postage is free:
    http://www.ebay.com.au/itm/Involute-...item3f45ebc89d
    And no time spent on painfully grinding a form tool (M0.3 is pretty small, you may even need to buy a tiny ponted grinding wheel to make it). And if the profile you grind is not quite right you are left living with a sloppy or sticky gear in your microscope.

    I have previosly bought several such sets, from another seller in Ukraine. These are new old stock from the Soviet time. They usually have some stains and some may even have light surface rust - no surprise after 20+ Years storage. Being form cutters, these are easy to re-sharpen if necessary. It may not be the best quality HSS, but hey at that price who cares, and if its only hobby use they do not need to last to cut 5000 tooth... One set that I only needed once (it was an odd Module dimension, M0.9 if I remember well) I even sold it again on eBay for more than what I originally paid for. Standard postage may turn out to be faster than ordering such a set from Australia for 4 times the money. And if you bought such a set in Australia and decided to sell it after you made your gear, you would only get 20 or 30% of your outlay back.

  9. #8
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    68
    Posts
    5,634

    Default

    Well, it's looking pretty much like I'm stumped before I even start. I have no way of creating 107 divisions. 106 and 108 , sure.

    Thank you all for your suggestions.

    Bob.

  10. #9
    Join Date
    May 2015
    Location
    Richmond
    Posts
    18

    Default

    Quote Originally Posted by Anorak Bob View Post
    Well, it's looking pretty much like I'm stumped before I even start. I have no way of creating 107 divisions. 106 and 108 , sure.

    Thank you all for your suggestions.

    Bob.
    Bob, what dividing head do you have? Do you have a rotary table? If so you could make a special 107 plate for your dividing head on the rotary table without the need for differential indexing. Just a thought! Then again, if you only want one off then just use the calculated angular spacing on the rotary table.

  11. #10
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    7,775

    Default

    I'm not so sure I'd be worry about plates.
    If you dividing head is 90 turns and my maths is right. If you just dial in deg,min.sec*, your greatest error would be something like 1 min 20 second**. Is that really going to worry anything?
    If so then make a plate as above and use that to divide your gear. The error will be 1/90th of the above.

    If you're still not happy, use that plate to make another plate

    Failing that you can use x/y coordinates and mill yourself one

    Regards being "left living with a sloppy or sticky gear in your microscope"
    I would have thought the gear train was spring loaded so a "little sloopy" wouldn't hurt anything as the backlash will be removed????

    Stuart

    *I've done it for 41 divs and had to go around 4 time I think, but I only went to the nearest minute.

    ** still checking that.. it might be even less. Much like "how close does thread pitch need to be... how close do teeth have to be to perfect?

  12. #11
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    7,775

    Default

    Changed my mind, the error would be (in theory) a max of 5 seconds....I wonder if the worn is anything like that good anyway?

    Stuart

  13. #12
    Join Date
    Nov 2010
    Location
    Gippsland Victoria
    Posts
    706

    Default CAD + 3d print ?

    Bob,

    You could make a cad file of the gear wheel and send it to a 3d printing place and they could make one for you. Might be expensive, but you've probably got access to the 3d printing folk on this forum who might help. Exchange favours with somebody.

    There would be a few packages around nowadays that you could do that with. You just key in all the data and it draws the part ie Z teeth Y pressure angle X module etc examples would be inkscape, or gearotic, or the woodgears prgram.

    However it could be offensive to the mindset of the bloke in the shed who wants to do all the interesting stuff himself, but I wouldn't tell anyone if you did it.

    Bill

  14. #13
    Join Date
    Jun 2008
    Location
    Victoria, Australia
    Age
    71
    Posts
    6,127

    Default

    Quote Originally Posted by Stustoys View Post
    I'm not so sure I'd be worry about plates.
    If you dividing head is 90 turns and my maths is right. If you just dial in deg,min.sec*, your greatest error would be something like 1 min 20 second**. Is that really going to worry anything?
    If so then make a plate as above and use that to divide your gear. The error will be 1/90th of the above.

    If you're still not happy, use that plate to make another plate

    Failing that you can use x/y coordinates and mill yourself one

    Regards being "left living with a sloppy or sticky gear in your microscope"
    I would have thought the gear train was spring loaded so a "little sloopy" wouldn't hurt anything as the backlash will be removed????

    Stuart

    *I've done it for 41 divs and had to go around 4 time I think, but I only went to the nearest minute.

    ** still checking that.. it might be even less. Much like "how close does thread pitch need to be... how close do teeth have to be to perfect?
    Hi Stuart, BT,

    Making the dividing plate wouldn't be too hard, with the PCD program in the DRO it would be easy enough? ( famous last words)

    I looked through the box of cutters I picked up in an auction lot, smallest was 0.5, I thought there were smaller ones in there, but no joy ( sorry).

    Ray

  15. #14
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    68
    Posts
    5,634

    Default

    Quote Originally Posted by OldRustyToolie View Post
    Bob, what dividing head do you have? Do you have a rotary table? If so you could make a special 107 plate for your dividing head on the rotary table without the need for differential indexing. Just a thought! Then again, if you only want one off then just use the calculated angular spacing on the rotary table.
    One of these Rusty - The direct indexing plate and arm can be removed and replaced with a worm and division plates.

    045 (Large).JPG

    A plate could be knocked up I guess using the rotary table.

    Quote Originally Posted by Stustoys View Post
    I'm not so sure I'd be worry about plates.
    If you dividing head is 90 turns and my maths is right. If you just dial in deg,min.sec*, your greatest error would be something like 1 min 20 second**. Is that really going to worry anything?
    If so then make a plate as above and use that to divide your gear. The error will be 1/90th of the above.

    If you're still not happy, use that plate to make another plate

    Failing that you can use x/y coordinates and mill yourself one

    Regards being "left living with a sloppy or sticky gear in your microscope"
    I would have thought the gear train was spring loaded so a "little sloopy" wouldn't hurt anything as the backlash will be removed????

    Stuart

    *I've done it for 41 divs and had to go around 4 time I think, but I only went to the nearest minute.

    ** still checking that.. it might be even less. Much like "how close does thread pitch need to be... how close do teeth have to be to perfect?
    Stu, Schaublin use a 60:1 ratio.

    Quote Originally Posted by steamingbill View Post
    Bob,

    You could make a cad file of the gear wheel and send it to a 3d printing place and they could make one for you. Might be expensive, but you've probably got access to the 3d printing folk on this forum who might help. Exchange favours with somebody.

    There would be a few packages around nowadays that you could do that with. You just key in all the data and it draws the part ie Z teeth Y pressure angle X module etc examples would be inkscape, or gearotic, or the woodgears prgram.

    However it could be offensive to the mindset of the bloke in the shed who wants to do all the interesting stuff himself, but I wouldn't tell anyone if you did it.

    Bill
    Bill, we have a 3D printer at work. I asked whether it would be capable of recreating the gear and was told that it wouldn't. It's used for small architectural model making. From what I have seen of its creations, they lack fine detail. The bloke most versed in the use of the printer did tell me how I could go about having the gear printed by an outside source. My problem was/is the production of the drawing. The only bloke in the office who would have an inkling of what a pressure angle is can't draw in CAD. I'll ask about the programs you mention tomorrow.

    As far as the DIY thing goes, I'd buy a gear it it was available rather than fool around making one. The stainless gear that Vernon linked to has an appeal but I don't know how well and for how long it would work with the brass gear that it would engage given Nikon's choice of nylon for the 107 tooth gear.

    Bob.

    PS thanks for looking Ray.
    Last edited by Anorak Bob; 19th Aug 2015 at 01:00 AM. Reason: PS added

  16. #15
    Join Date
    Oct 2011
    Location
    Adelaide
    Age
    56
    Posts
    3,149

    Default

    Quote Originally Posted by steamingbill View Post
    You could make a cad file of the gear wheel and send it to a 3d printing place and they could make one for you.
    The design of these gears is that they are pressed onto a bearing outer - so the gear itself is under (circumferential) tension when installed. Chances are that is why the original one broke. It depends on the process but some of these printed parts are nowhere near as strong as the solid material that you would otherwise use. The teeth on this gear are only 0.65mm high too, so would need really good definition. While I'm not saying that a 3D printer could not do it I think you would be running up against practical difficulties getting the detail fine enough in a part that has sufficient strength.

    Michael

Page 1 of 7 123456 ... LastLast

Similar Threads

  1. CNC Machines for gear cutting
    By MPW in forum CNC Machines
    Replies: 11
    Last Post: 12th Nov 2013, 08:05 AM
  2. FESTOOL query #2 Ė Precisio 70 or TS 75 with a CMS module
    By FenceFurniture in forum FESTOOL FORUM
    Replies: 11
    Last Post: 8th Mar 2011, 08:45 AM
  3. gear cutting questions
    By lather in forum METALWORK FORUM
    Replies: 8
    Last Post: 7th Feb 2011, 10:18 AM
  4. Gear cutting
    By funkychicken in forum METALWORK FORUM
    Replies: 9
    Last Post: 28th Aug 2009, 10:21 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •