Gear Cutters

[Brian Rupnow]

Mosey---I did make a single point gear cutter myself, as shown in the picture, and I did cut two gears which mesh well. I ground the tooth profile of the cutter from 01 steel to match an existing gear that I already had and flame hardened it . Although it worked, I was not terribly happy with the shape of the gear teeth, and I found that the single point contacting my aluminum blanks seemed to place a lot of impact stress on my small mill. It is definitly possible to do this. Captain Jerry did the same thing at about the same time and was very pleased with his results. I have been fortunate to find a very lucrative design project this fall which has given me some unexpected cash, so I thought I would treat myself to a set of gear cutters and some 1-2-3 blocks.

 

[tel]

Couldn't find any dimes, here's some 40 dp with quarters

 

[kcmillin]

Brian, which cutters are you looking at to get the $400+ price tag? From what I seen, cutters between 20 and 48 DP (or pitch diameter as they refer to it as) are about $31-$33 US a piece. (Not a whole lot different in Canadian Dollars) If you buy one, they should :hDe: send you a coupon for 20% off your next order. Although pushing $250 is a lot of scrilla, it don't sound as bad as $400.

Here is a picture of a 48DP 12 tooth 45degree bevel gear made with an involute cutter.

Sorry no coin, this is an old pic.

the major diameter is less than .5". The same tooth count in a pinion gear is less than .3".

Kel

 

[Brian Rupnow]

Thanks Tel--Very kind of you to post that picture for me. The 40 dp seems a bit large to me, but I think thats what I have on many of my salvaged small gear sets I have used on various small machines I have built. I am going to do a web search and see if I can find some 1:1 pictures of various tooth profiles. I know I have seen them in engineering catalogues in the past, but right now I can't remember what catalogue it was.

 

[Brian Rupnow]

Thanks for the picture Kcmillin.

 

[steam5]

I am also thinking of buying a set of cutters thanks everone for all that Info. its been a great help.

Charles

 

[Mosey]

Isn't it great what you can do when you don't know any better? Here is a hob and some gears that I made for my Silver Bullet. I think the're OK. What do you think?

 

[doc1955]

I like this place they have a gear search tool and you can down load the gear in the form of 3d cad.
Once you have it down loaded you can create a cutter from it to the correct profile it is a simple process.
Then just create a full size drawing throw on some dims and you have a map to go by. I've done all my gears for my engines with a single point method I try to keep the over all cutter dia as small as I can this will help with the pounding and make a nice smooth cut.


Sorry forgot the link Spur gear cad files

View attachment Gear.cutter.48.pdf

 

[tel]

I've been getting my module cutters from here. About the cheapest I've found available to Oz and they seem to be ok.

 

[Blogwitch]

If you get a chance, watch a DVD called 'Making gears the easy way'

http://littlemachineshop.com/products/product_view.php?ProductID=2057

It is boring as hell with his monotone voice for four hours, expect to fall asleep a couple of times, and he makes some glaring mistakes, but he does show very easy methods to make all your own tooling and how to use it in such a way to produce gears that work. They might not be absolutely spot on, but they will work just fine.

I have a full set of commercial MOD and DP hobs in sizes that go up to gears for my machines, and I will be trying out one of his proven easy methods of using them when I eventually get back in the shop.


John

 

[cfellows]

Brian, thanks for the kind words... flattery will get you everywhere!

The 24 pitch gears have been fine for engines I've built todate, but I've been thinking of building some smaller engines which would require smaller gears. A 32 pitch gear would be 25% smaller for the same number of teeth than a 24 pitch.

In general, if you don't need the tooth strength of a courser pitch such as 24DP, finer pitch gear cutters like the 32DP give you more options... you can make smaller gears and if you need a bigger gear, just design it with more teeth.

I've never tried making my own gear cutter since the commercial involute cutters are easy to use and yield results close to commercially available gears.

Chuck

 

[lee9966]

I mentioned earlier buying conical mills to make a fly-cutter type of cutter. Below are the links that made me want to try this. I just made a test cutter 24DP 17-20 tooth and it looks fine to me, although I haven't tried it yet.

The idea of using conical mills: http://bbs.homeshopmachinist.net/showthread.php?t=42051

Some useful info on making button shaped cutters http://metalwebnews.com/howto/gear/gear1.html

A 3 degree mill from www.Travers.com seems to work well. And yes, they do send a 20% off coupon which arrived in the mail even before the mills did.

Lee

 

[doc1955]

You really do not need relief on the side of a single point gear cutter just put your blank you want the profile on in your vise at a 2 to 5 degree angle and mill end to profile needed.
All the single point gear cutters I have made have been made that way and I (knock on wood) have always had good luck with them.
The largest one I made was a number 2 dp for a governor gear in a 5 hp old International hit miss engine and it has been working fine for 20 years now.
Anyway the only way I would buy a gear cutter is if I had a job come into the shop where I had to cut a large lot of gears this one and two gears here and there in my opinion doesn't justify buying a cutter. It just may be my cheap side coming out :big: :big:

 

[tel]

When the urge to make gears first struck me I went down the fly cutter route - for a while. using the Ivan Laws info for buttons. Frankly, for what a cutter costs these days it's just not worth all the extra effort, to say nothing of the much slower cutting time.

 

[Brian Rupnow]

Today I remembered that I had purchased a set of gears when I built my Webster engine. I looked up the plans, and identified them as 32dp gears. Pulled the Webster engine down off the shelf, blew off the cobwebs and had a look. Now I know what 32 dp gears look like. They actually look pretty good. Now I have to find a 24dp gear to get a good visual comparison.

 

[doc1955]

I know this is asking a lot, but can anyone post a picture of their particular gear "size/type" along with a coin about the size of a Canadian or American dime so that I can see the tooth profile?---Please

These are 48dp gears they are for the tiny's that I'm attempting :big: to build.

They were cut wit this tool at 3200rpm and full depth cut at approximately 25 IPM
I wouldn't attempt that on a larger gear but for these small gears full depth and climb cutting works just fine.

 

[Brian Rupnow]

Thanks Doc1955---I'm rather torn here. Chuck says that the 24dp work for most stuff he does, but they are slightly larger than the 32 dp. As I get older, my eyes aren't going to get better. That says to me that maybe the 24 dp would be my best bet, even if they are a bit larger.--at least I will be able to see them more clearly. Quite frankly, I've built a few Elmer Verbourg engines at their original size, and I find that the components are right on the ragged edge of what I can comfortably see and deal with. I think that perhaps the 40 and 48s are a bit too large, based on the pictures that you and Tel have posted.

 

[cfellows]

Brian, I think you'll be happy with 24DP. A 12 tooth gear has a pitch diameter of 1/2" and and overall diameter of about .583". You can also buy 9 tooth pinion wire which is basically a 9 tooth gear in any length you want, then cut off whatever you need for 1 gear. A 24 pitch 9 tooth gear has a pitch diameter of 3/8".

http://www.google.com/imgres?q=pinion+wire&hl=en&sa=X&biw=1280&bih=909&tbm=isch&prmd=imvns&tbnid=uiu6zI394khuUM:&imgrefurl=http://www.sdp-si.com/web/html/gears.htm&docid=Yo-7dnndIjuDHM&imgurl=http://www.sdp-si.com/web/images/product_images/Gears/Pinion-Wire.jpg&w=366&h=419&ei=0bkPT5nQIYme2AXB88jSAg&zoom=1&iact=hc&vpx=323&vpy=304&dur=1119&hovh=240&hovw=210&tx=111&ty=149&sig=108105500657566937077&page=1&tbnh=136&tbnw=119&start=0&ndsp=30&ved=1t:429,r:1,s:0

Here is a 24DP cutter set on ebay for a pretty good price.

http://www.ebay.com/itm/Lot-8pc-Dp24-14-1-2degree-PA-1-8-Involute-Gear-Cutters-/280800512976?pt=LH_DefaultDomain_0&hash=item416103cbd0#ht_733wt_952

Chuck

Edit: Brian, if you look at this thread of my horizontal 4 cylinder engine, you there's a pretty good picture of a 24 DP gear in reply #119. It's 1.25" (pitch) diameter and has 32 teeth. The round propeller hub below the gear is 3/4" diameter, about the size of a U.S. Penny.

http://www.homemodelenginemachinist.com/index.php?topic=3677.30

Chuck

 

[Maryak]

Most of the better CAD programs have a gear contour function.

In my Turbocad professional, you input the basic parameters DP, PA, No of teeth and voila an actual size plan is produced. Make the same gear using different DP's and they can be compared visually.

Best Regards
Bob

View attachment gear.pdf

 

[Brian Rupnow]

Well, the die is cast!!! First thing I found out, is that I can not order from Travers in the States. I have to order from Travers in Canada (Quebec). Second thing I found out is that the 20%off coupon business applies only in the States.----Damn!!! Third thing I found out is that they don't have an arbor with an MT2 shank, so I ordered a 3/4" straight shank. I bought the complete set of eight 24dp cutters. 14 1/2 degree pressure angle. They are 1.75" outer diameter. Costs were $422.49 for all 8 cutters and the arbor. (the arbor cost $123.00) Tax will be $33.80, and shipping will be $9.95, for a grand total of $466.24. I asked the clerk there if I could exchange the set of 24dp gears for a set of 32dp gear if I didn't like them. She said yes, and that although there was normally a 35% restocking charge she would put a note on my file requesting only a 5% restocking charge plus cost of shipping.---Sure hope I like them!!!---Brian