gear cutting tools

[aero]

1) Who sells a decent selection of vertical mill gear cutting tools (not hobs)? Or - who sells them at all??? Looking for metric as well as inch.

2) I am going to be purchasing a mill soon (and dividing head assuming a rotary table won't be accurate enough for gear cutting) - it seems from reading recent posts that the Grizzly machines are decent?

[SGW]

Several companies sell gear cutters; MSC (http://www.mscdirect.com) is probably the most well-known although others may have a better selection, I'm not sure.

A rotary table would be perfectly adequate for use in cutting gears, although it may be somewhat inconveient to set up the work. You need to "somehow" hold the gear blank so you can get at it with the gear cutter, and on a rotary table that may take some imagination. You would also need a rotary table that can be set vertically (a horizontal/vertical model). A dividing head would probably be a lot easier to use, but a rotary table would certainly be accurate enough for anything you're likely to be doing.

I've never seen a Grizzly mill; I have seen Jet, and think they are pretty good. I have seen Enco, and I am unimpressed.

[Ben Shank]

If you are going to do any serious gear cutting you really need a dividing head and a horizontal mill, a verticl mill isn't ridgid enuff and is going to be a pain to setup. The arbor in a vertical mill doesn't have any support on the outboard end allowing it to flex. For very light ocassional work you can do it but if you have very many to do a horizontal is the only way to go,,

[John Stevenson]

<font face="Verdana, Arial" size="2">Originally posted by Ben Shank:
If you are going to do any serious gear cutting you really need a dividing head and a horizontal mill, a verticl mill isn't ridgid enuff and is going to be a pain to setup. The arbor in a vertical mill doesn't have any support on the outboard end allowing it to flex. For very light ocassional work you can do it but if you have very many to do a horizontal is the only way to go,,</font>

Don't forget though that Bridgeport do a horizontal attachment for their verticals.
Chances are it also fits the clones.



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Regards,
John Stevenson,
Nottingham, England

[Ben Shank]

John,
You could probably buy horizontal over here cheaper than you could buy a Bridgeport attachment, if you could find one. Just my $.02 worth

[John Stevenson]

Ben,
I was just making a point. I fully agree that a horizontal is far better but I was just trying to point out an alternative bearing in mind that most people have a space problem and may have a vertical mill already.
We have J&L in the UK as you do, they often list these as specials for about 250 UKP, thats about $360. Possibly a lot to spend but taking something like distance and shipping in the US even a free horizontal will possibly cost the same.
Another plus that a lot of people don't realise with the horizontal attachment is that it's actually a right angle drive and will take the standard R8 collets. Very handy if you need to work on the side of large pieces.

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Regards,
John Stevenson,
Nottingham, England

[Ben Shank]

John,
I agree that the attachment is a nice thing to have and if one is short on space or just wants all the gadgets that came with the mill it's nice to have. But seeing manual horizontals selling at auctions for less than $100.00 us, they are dirt cheap right now.

[John Stevenson]

<font face="Verdana, Arial" size="2">Originally posted by Ben Shank:
John,
I agree that the attachment is a nice thing to have and if one is short on space or just wants all the gadgets that came with the mill it's nice to have. But seeing manual horizontals selling at auctions for less than $100.00 us, they are dirt cheap right now.</font>

Ben,
AGAIN I'm not stating that one is better than the other - just pointing out alternatives.
Hell if you have the room go for it. They are real work horses. I have a Victoria U2, bed size about the same a Bridgeport. I make toolholders for North Sea oil rig boring tools. This machine puts a 7/8"wide by 7/8" deep slot in the holder in one pass.
As regards cost though work out the full cost. Take the auction price, add the sales percentage, usually 10%, add shipping and add your time off work going to the auction.
Another thing to watch is that horizontals were bought in industry for heavy work and usually show signs of such. If you get a chance get one with a vertical head so you have the best of both worlds but beware not many have a moveable quill so and angle work like boring motorcycle valve seats still require you to set the job at an angle as opposed to setting the head at an angle.

PS. They are that cheap over here that you can't give them away. Peter Forbes over on RCM was trying to give a small Adcock and Shipley away about a month ago. He got no offers and dumped it off on me so I could rob the main ISO 40 spindle out of it for using as a dummy to machine special holders. Once someone else collects the motor it's going in the scrap.

------------------
Regards,
John Stevenson,
Nottingham, England

[This message has been edited by John Stevenson (edited 05-02-2001).]

[aero]

Thanks for the replies - I will mostly be cutting small steel gears and also plastic gears - very very low quantities (hobby work). I think a vertical mill will work fine for this. My problem is finding a distributor for metric gear cutters that will sell to the home user (non-commercial sale).
Anyone have any experience with the rotary table / dividing head combinations? Grizzly sells one (they sell dividing head add-ons for their rotary table) and for what I need it for (gear cutting as mentioned above above) it seems like it should work fine.

[Ben Shank]

John,
I don't have room for another machine, but if one comes along, I'm sure it will be crammed into the shop somewhere, I think I'm running an "old folks home" for vintage machines and other "orphans" that need a home!
No, I'm not arguing the vert vs horiz, just wanted to point out that horizontals are cheap rite now, and may be a better deal than a horizontal attachment. I have a B&S horiz'l with vertical atachment and it has no moveable quill in it.

[Ron LaDow]

Aero,
I just got a 'super spacer' from Enco. I got it because I needed it in the past, didn't have the money, and had to work around it. I have the money just now.
Point is, I haven't used it yet. But it certainly looks like it will suffice for both rotary table work and dividing head work. And it does come with both a chuck and a face plate. A two-fer...

[Ken S]

I purchased some from Travers Tool. I do not use a dividing head - rather I adapted the excellent method described by Rudy Kouphout in HSM some time back. If you have a "master gear or gears", you do not need a dividing head. I have some pix of the one I made on my website, and have found it to be very useful. see profile for web address.

Ken

[SGW]

I think for some things you do need a dividing head or rotary table. I don't think there is any way, for instance, to use a "super spacer" to make a 47-tooth gear.

[John Stevenson]

<font face="Verdana, Arial" size="2">Originally posted by Ben Shank:
If you are going to do any serious gear cutting you really need a dividing head and a horizontal mill, a verticl mill isn't ridgid enuff and is going to be a pain to setup. The arbor in a vertical mill doesn't have any support on the outboard end allowing it to flex. For very light ocassional work you can do it but if you have very many to do a horizontal is the only way to go,,</font>

Ben and list,
Just spotted this is a magazine. Thought I'd share it. Looks very cheap and simple to make.
http://homepage.ntlworld.com/machines/vertical%20support.jpg



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Regards,
John Stevenson,
Nottingham, England

[artificer in metal]

Depending on the pressure angle of the gears you can find some machine tool places that will sell cutters. Problem with this a set is eight cutters and thats for each size of tooth (diametral pitch) and as far as I know only really available for 14 degree pressure angle (I would want at least 20 and better 25 degree pressure angle). It depends on the material you are cutting the gear in but your solution may be to free hand grind a form tool in a HSS blank(use a gauge to assist you and good luck - its a challenge!).

[SGW]

While you need a complete set of 8 cutters to cut the full range of teeth of a given diameteral pitch (from about 12 teeth to a straight rack), for any given number of teeth you need only one cutter, which in the MSC catalog seems to be about $27 if memory serves. Unless you're doing a lot of gear cutting, it's highly unlikely you'd need a complete set of cutters.

MSC sells both 14 1/2 and 20 degree pressure angle cutters, I believe.

An alternative is to use a circular approximation cutter, as described by Ivan Law in his book "Gears and Gear Cutting." For any given number of teeth, you can pretty closely approximate the "correct" involute form with a circular segment. In fact, a correct circular segment will be closer than what you get with a gear cutter used at the ends of its range. See the book for details.

[John Stevenson]

<font face="Verdana, Arial" size="2">Originally posted by SGW:
An alternative is to use a circular approximation cutter, as described by Ivan Law in his book "Gears and Gear Cutting." For any given number of teeth, you can pretty closely approximate the "correct" involute form with a circular segment. In fact, a correct circular segment will be closer than what you get with a gear cutter used at the ends of its range. See the book for details.</font>

Similar article can be read at :-
http://www.metalwebnews.com/howto/gear/gear1.html




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Regards,
John Stevenson,
Nottingham, England

[Rob]

Where are the $100 horizontal mills at? I don't have the room but Im sure I can find a place for it.

[Jim Hubbell]

I have made a number of 16 and 32 DP gears which I am now using as spare change gears on my Atlas 10 in lathe. A 6in rotary table and homemade tailstock with homemade mandral does just fine. I got my cutters from VME that advertises in HSM. My Jet Mill/drill does the job.

[phil burman]

An easy way to make a gear cutter is to cut five or six groves in a bar of silver steel (drill rod) with the form of the equivalent rack for the gear DP you wish to make. This is easy because the rack form has straight flanks. You then gash it longitudinal say 6 times at equally spaced distances around the circumference and this forms a series of cutting teeth. Harden and temper then stone the cutting faces and you are ready to go.

The method of use in a vertical mill is to set the center cutting tooth on the gear blank center height then take say a 5 thou cut across the blank. Index to the next tooth and repeat. Once you have been all the way round add another 5 thou and repeat. Repeat until at full depth. This method is good for light machines as you only nibble away small amounts all the way to full depth. With the normal form cutters sooner or later you have to take a full width cut.

This method worked fine for making gears in silver steel. I then hardened and tempered the gears and cleaned up the gear tooth flanks by running the gears together for a short period with a fine grinding compound. This method produces a very nice matched pair, but possibly not so good for interchangability with other gears.

I’m surprised that this method is not discussed in Ivan Laws excellent book on gears and gear cutting.

Best Regards
Phil

[franco]

Aero,

I have a 6" Vertex H/V rotary table with the optional dividing kit. I have used it on a mill drill to cut several gears, including some 16DP lathe change wheels. The Vertex tables have a MT socket in the table center, 2MT on the 6" tables or 3MT on the 8" tables. I made an adapter to fit the socket which will accept the 4" 3 jaw chuck or 6" 4 jaw chuck from one of the lathes. Also made a tail stock to suit.

For the gears I have made I ground form tools and used these in a fly cutter. It is slow, but cheap, and the gears turned out OK.

If you go the rotary table way, be aware that it quite possibly will not fit the slots in your mill table, so an adapter plate may be required.

As a matter of interest, I eventually bought the Vertex tailstock to suit the 6" rotary table, and was disappointed with it - the fits and finish on the one I got are not up to the standard of the rotary table itself. I also had to make an adapter plate for it so the height matched the R/T when mounted on its adapter plate. I still tend to use the home made tailstock for this job.

Regards,

franco

[phil burman]

I forgot to say that one of the big advantages of this gear cutting method is that you only need one cutter for any number of gear teeth for a given DP.

Phil

[bpsbtoolman]

I have been interested in gear cutting for many years. ( I'm 81 ) and up until a few years ago have been getting gear cutters in ones and twos and auctions for a few bucks each. So I now have most cutters for 14-1/2 PA in DP of 20,18,16, and a few bigger and smaller. Since Boston Gear does not sell 18 PD used on my 9A, I make my own gears on a Sheldon horisontal mill that matches my Sheldon 12" shaper. For my Toolroom Heavy ten I have made a set of 100/127 gears for metric cutting. I bought the Shelon mill from a guy that had it listed as a horizontal mill, not.
I have always been interested in hobbing gears and considering putting a hobbing extension on my H mill. A very interesting event occured a few years ago when the Western Machine Co that made Steptoe shapers in Holand, Michigan a few miles from me sold out after being shut down for many years. They were selling or almost giving away just about everything a large tool company. I saw straight edges 5' and shorter sell for peanuts. Drills , reamers, both square and acme taps. Me and the guys were in hog heaven.My friend and I were picking up castings and steel stock for future projects. My horizontal mill came with a 1" No. 9 B & S arbor. Some of my gear currers were 7/8" bore. They had a pile of these in 7/8" and I bought one for cheap. I told my 2 friends about it and the next day decided to get a couple more, But then the only one left was one without coulars that I bought anyway.
The machines were the only thing they had a bid auction on. I looked at a small gear hobber that used conventional hobs and wondered what it would cost. I even bought a new 16 Dp hob in anticipation. You could call in a bid and a few days later I called and asked what the bid was. The girl said they had none. I jokenly said one dollar and she said $ 100 would do it. My friend said he would loan me his truck to haul it home to my walkout basement shop that has a 2 ton I beam just outside the door.. I gave it some serious thought, but I was pushing 80 years old and thought I should be cutting back. I am still thinking what a deal I missed. Bet you know, water under the bridge.
Anybody got a true story to match mine?
Walt

[J Tiers]

The difference between the rotary table and the dividing head is two-fold.

One, the dividing is simple with the head, and unless the rotary table emulates the dividing head, you have to count degrees etc. With the DH you simply count full crank turns and move the index arms to keep track of fractional turns.

Two, the rotary table is big, and gets in the way. The dividing head with T/S uses a mandrel to hold the blank clear of itself, and so allows easier access by the cutter.
It also presents the blank in a way that either a horizontal or vertical mill can get the cutter to the blank easily.

The horizontal mill is sturdier, more rigid, and, unless you have a universal mill, always in tram.

The ram-type vertical mill like bridgeport allows doing helical gears, which needs a universal mill for horizontal. But it is otherwise easy to have off tram, or get knocked off tram in the cut, unless it is a heavier type.

For cutters, Victor Machinery has cutters at reasonable prices for about any pitch and angle.

Gears may be non-critical, but if inaccurately made, will be noisy or even prone to lock up.

[This message has been edited by J Tiers (edited 02-02-2006).]