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 Posted: Fri Dec 08, 2006 5:15 am Post subject: Creating change gears for Emco Maximat 7... |
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Hi folks, I would like to try the project of creating some change gears
for my Lathe (since they seem to be generally unavailable).
| Quote: | From the best of my ability to determine... It looks like the Module is
1 (DP ~= 8)... However I have not figured out how (with my limited |
tools) to determine the pressure angle.
Can anybody help me out here and point me to the correct Involute
Cutters for these gears?
Thanks in advance,
Mike |
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| Posted: Fri Dec 08, 2006 11:44 pm Post subject: Re: Creating change gears for Emco Maximat 7... |
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Thanks again for your response George.
Comments again inline.
| Quote: | Be setting down when you price the metric involute gear cutters
and stub arbor.
For proper mesh you will need an actual 1.00 mm module cutter.
This xlates to 25.4 pitch and a 26 DP cutter won't be close
enough. Depending on the tooth range of the gears you may need
two [#2 & #3], as these are good for a limited range of teeth.
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Rats,
Okay, I'll have to get the module gear cutters. I have a 1" MT2 Stub
arbor so I guess I'll be getting the gear cutters here:
http://www.rdgtools.co.uk/acatalog/_1_MODUL_E_GEAR_CUTTERS.html
At $20/each US it's not too painful.
More comments below...
| Quote: | My copy of Law indicates:
cutter # tooth count
1 135 - rack
2 55 - 134
3 35 - 54
4 26 - 34
5 21 - 25
6 17 - 20
Be aware this is a Brit book (#17 in the Workshop Practice
Series) and the cutter identification may be different in the US.
The change gears for my Emco compact 10 with a 8 TPI leadscrew
and 30 tooth gear machined in the spindle are:
30,40,60,90,120 ship (with the lathe as stock).
35, 45,50,55,65,70,80,95 and 100 are supplied as the "set of inch
change gears" as p/n301-210 (extra cost option and no longer
available).
The metric change gear set includes the above plus a 75 tooth
gear p/n B5Z-200-010
I have scanned the Emco manual and posted it in pdf format on my
website. See this for complete thread information.
gotohttp://mcduffee-associates.us/machining/emcoLathes.htm
and scroll to the bottom of the page.
you want
spm20-30.pdf and im20-29.pdf
There is no 127 tooth metric change gear available. However you
can use some odd combinations to approximate the required 1.27:1
conversion ratio such as
89/70 1.2714:1
57/45 1.2667:1
61:48 1.2708:1
66:52 1.2692:1
and a whole bunch more.
You may also want to consider the gearing required to generate
module and diametric pitch threads if you will be machining any
worms. All of these will involve an attempt to approximate pi.
3.1416...:1
You will also need some way to index the gear for cutting such as
a dividing head or rotary table with indexing plates. You can
use a vertical/horizontal rotary table with an angle veneer, but
will have slightly less accurate gears, which may well be "good
enough" for your purposes.
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I have a Vertical/Horizontal rotary table with indexing plates.
Hopefully it will be "Good enough"
| Quote: | see:http://wttool.resultspage.com/search?p=Q&ts=custom&uid=956095168&srid...http://littlemachineshop.com/products/product_search.php?critFast=rot...http://www.use-enco.com/CGI/INSRIT?PMAKA=890-9612&PMPXNO=4841009&PART...
note that the dividing plates and index arm is generally not
included with the rotary index table.
You will also need an arbor to hold the gear. We made on in
class from a 6 inch 3/4 UNF bolt. Turn the head off, and drill
each end for centers. Hold the bolt between centers and machine
a #2 MT [almost all the smaller dividing heads and rotary tables
have a #2 MT, but check as some have B&S taper as do many of the
older ones] Skim cut or file the threads to as close to 19 mm /
0.748 inches diameter as possible. Clamp the gear blank between
two 3/4 UNF nuts. We also drilled and tapped the #2 end with a
1/4 X 20 thread for a "draw bar."
Drill a 1/8 hole where the keyway will go for a guide when
filing.
The gear blank is a good face plate job.
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My friend suggested the following:
1) Pilot bore a 1/8" hole in bar and turn the end to the proper OD.
2) Start parting off the gear blank but only go ~ 1/3 of the way or at
least more than tooth depth
3) Chuck up bar in rotary table and mill the teeth.
4) Return the bar to the lathe and finish parting off. (So you have
gear with 1/8" center bore)
5) Chuck a piece of fine grained hardwood in four jaw chuck and machine
a flat bottomed hole in the end grain slighly deeper than the gear is
thick, and slightly smaller than the OD of the gear.
6) Drill 1/8" hole into end of hardwood and leave drill sticking out an
inch or so.
7) Place the gear over the drill rod and press into the hardwood.
8) Remove the drill rod and carefully bore.
9) Broach keyway if needed.
However, since I'm probably going to be making several gears with the
same arbor size and the Gears I'm making are heavier duty than the ones
he usually makes, I think your method sounds better suited to the task
at hand.
| Quote: |
Enco sells 1/2 inch X 4 inch X 3 and 6 foot pieces of 6061 T6
aluminum. Steel will be much more difficult to machine.
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I've been think I would do this out of aluminum or brass, with brass
being "prettier" and Aluminum being more cost effective.
| Quote: |
Unka' George (George McDuffee)
..............................
Only in Britain could it be thought
a defect to be "too clever by half."
The probability is that too many people
are too stupid by three-quarters.
John Major (b. 1943),
British Conservative politician, prime minister.
Quoted in: Observer (London, 7 July 1991). |
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