WHERE ARE THE SHAPER USERS ?

[Mike BondarczukParticipant @mikebondarczuk27171]

Hi all,

Just found this thread and find it fascinating and great to see that shapers are still in use in some home workshops.

I have an imperial 8" Boxford which produces a superb flat surface which I generate as a base for my stationary engines.

Don't have any pics on my profile yet of it bit will post some very soon.

Mike

[NobbyParticipant @nobby]

I sometime uses my Drummond hand shaper for surface grinding
Nobby

[Mike E.Participant @mikee-85511]

Posted by Nobby on 21/09/2016 12:55:27:

I sometime uses my Drummond hand shaper for surface grinding
Nobby

Surface grinding on a shaper? That's an interesting idea, but would have to be approached cautiously under power. Food for thought, as I have a small tool post grinder.

Can't add much to what's already been mentioned, but it's nice to see that a lot of old machines are being restored and used. Shapers really are not obsolete, as they can still do jobs that the machines which superseded them can, and with simple and less expensive cutters.

I have an Ammco 7" shaper of World War 2 vintage, and although it doesn't get a lot of use, its one of my favourite tools, doesn't take up a lot of room, and considered a lifetime keeper. Last year it made a long voyage with other selected tools across the big pond, and is in storage until my new 350 sq. ft. garage / workshop is built.

Sorry about the picture quality, but at the moment I only have a couple of old photos of the shaper in the Album I started; one where it can be seen at the back of my old garage, and the other which I took for an inventory purpose. I'll post better photos once the new shop is set up.

[Gray62Participant @gray62]

I have a boxford Mk2 8" shaper which gets regular use, here it is pictured on the SMEE stand at MEX 2014 coupled with a divisionmaster controlled dividing head cutting an internal gear

[John CoatesParticipant @johncoates48577]

Here's my Elliott 10M. Love setting it going then hearing it swish swish in the background as I get on with something else

[Ady1Participant @ady1]

I'm having a go at making 4×30 tooth gears at the moment

[steveteeParticipant @stevetee]

I was about to mention the shaper for cutting gears . I saw a jig some one one had made, every stroke incremented round 1 tooth, every rotation added a thou ( or 2) until the job was finished. Very clever.

[Gordon AParticipant @gordona]

I find my Adept number 2 hand shaper to be a good substitute for my poor filing skills.

The modification to the toolslide shown takes the guesswork out of depth of cut.

Gordon.

[Barry Taylor 3Participant @barrytaylor3]

Just came across this thread, I've got an Alba 1-A 10" shaper and I love it. Very similer to the 'Royal' shaper pictured here. I can shape most things within reason much quicker than with a vertical mill, although the two in combination is a great marriage.

Barry.

[RICHARD GREEN 2Participant @richardgreen2]

Hello Graeme W,

Nice to see your Boxford cutting an internal gear,

How do you work out the tool shape for an internal gear, and how do you create the tool shape accurately ?

I've cut plenty of gears using a commercial cutter in a horizontal mill,

At some point in the near future I am going to have to cut an internal gear, so I am interested how you achieved it.

Richard.

[david williams 14Participant @davidwilliams14]

fun to use the old boxford. part of the pleasure is deciding on best use of tooling – and the sounds of cutting. I agree satisfying monitoring it whilst engaged on other work.

certainly wont be getting rid of mine.

[Anonymous]

Posted by RICHARD GREEN 2 on 22/09/2016 11:12:05:

How do you work out the tool shape for an internal gear, and how do you create the tool shape accurately ?

I'd be interested in that too. Most of my gear books say it isn't as simple as the tooth space being the same as the tooth space for an external gear. But they then don't tell you what it actually is. As I understand it an internal gear is like an external gear turned inside out, but I'm having difficulty imagining the transformation.

Andrew

[Neil WyattModerator @neilwyatt]

Posted by Andrew Johnston on 22/09/2016 17:03:38:

Posted by RICHARD GREEN 2 on 22/09/2016 11:12:05:

How do you work out the tool shape for an internal gear, and how do you create the tool shape accurately ?

I'd be interested in that too. Most of my gear books say it isn't as simple as the tooth space being the same as the tooth space for an external gear.

All the practical examples I have come across say that they made the same shape as an external gear in negative.

So the cutter needs to be shaped like the TOOTH of an external gear not the tooth space, i.e. convex sides, not concave ones. You could generate a cutter using a rack-form hob.

Neil

[Michael ToppingParticipant @michaeltopping17870]

Last paying job I had was for a company who made high precision epicyclic gear boxes. All the internal gears were cut using standard gear shaping cutters, both dp and module. I know because I cuts lots of them. The cutters were imported from either the States or Switzerland and were mostly Hss with some in carbide, hideously expensive at about £1200 each depending on size.

Michael

[Anonymous]

Posted by Neil Wyatt on 22/09/2016 17:35:23:

All the practical examples I have come across say that they made the same shape as an external gear in negative.

So the cutter needs to be shaped like the TOOTH of an external gear not the tooth space, i.e. convex sides, not concave ones. You could generate a cutter using a rack-form hob.

Very possibly, but that cannot be exactly correct. The shape is indeed like the tooth of the external gear, but it is not identical to the mating gear tooth, or it would never work due to lack of clearance as the external gear rolled around the internal gear. What interests me is the theoretically correct shape for the cutter. Given that one would be machining the cutter anyway it makes sense to get it right.

Andrew

[Brian WoodParticipant @brianwood45127]

Machinery's Handbook makes the suggestion that the standard #1 cutter (135 T to rack for standard external teeth) will produce acceptable internal gear teeth of 4 DP and finer, and when there are 60 teeth or more to cut. The finer the pitch and larger the tooth count the better the result. It goes on to say that this approach is considered satisfactory for ordinary jobbing work and it warns that the use falls down badly when the tooth count of the pinion is large in proportion to that of the internal gear.

​The other advice offered is to reverse addendum and dedendum as they are defined for external spur gears.

A 20 degree involute full depth tool form is recommended, but 20 degree stub tooth and 14.5 degree full depth tooth are also used.
My older book on the subject only talks about the reversal of geometry and not the other information, but there were no helpful illustrations provided.

So make what you can from that
Regards
​

Brian

[Anonymous]

Posted by Brian Wood on 22/09/2016 18:56:23:

Machinery's Handbook makes the suggestion that the standard #1 cutter (135 T to rack for standard external teeth) will produce acceptable internal gear teeth of 4 DP and finer, and when there are 60 teeth or more to cut. The finer the pitch and larger the tooth count the better the result.

That's pretty much what my Gear Design Simplfied says too. I've never needed to make an internal gear, and I can't see a pressing need at the moment. But there must be a theoretically correct shape and my idle curiosity wants to know what it is; taking into account what happened to the cat of course. I also suspect that it is easier to make ones own arbitrarily shaped cutters now than it used to be; even HSS can be machined with the right tools. So the approximations necessary in days gone by are possibly less critical now.

Andrew

[Anonymous]

STOP PRESS: A trip round the internet resulted in me ending up on a thread from 'Practical Machinist' about cutting internal gears. A very knowledgeable old school member recommended the Gear Design Manual – Section II by Buckingham for internal gears. So I've taken a punt and ordered a secondhand copy from the US via Abe Books. I went mad and selected the priority delivery service for a total of £11.68p At least I don't have to break the bad news about the spending to a significant other. We'll see what turns in a couple of weeks time.

Andrew

PS: It's almost enough to persuade me to extract a digit and get my shaper repaired and running again.

[John PParticipant @johnp77052]

Seeing this shaper thread is going the way of internal gears i have
added some photos to the album "gears" that may be of interest to some.
The pair of gears here in this photo 1 & 2 are for a model wankel engine
rotor they are 1 mod 20 deg pa 14 tooth for the gear and 21 tooth
for the ring.The engine was from a design published in the
Aeromodeller annual 1971 by Julian Falecki the drawings show
some modification from standard size to avoid undercut on the 14
tooth gear ,the ring gear has the same modification to allow the gears to
mesh and also to obtain the correct centre distance 3.5 mm.
The next photo shows the hobbed broach made from a piece of
steel from the scrap box eventually case hardened.Although there
is no form relief the broach will cut well enough to produce a small
quantity of gears.This perhaps makes the point that the internal form
is the same as the same size spur gear ,however the broach has been
cut a little oversize to allow for some clearance.
Since the broach and gears are both hobbed this is an easy thing to do,
i dont know how this could be done using the usual form type of gear
cutter as you have to stick to correct pcd .

The third photo is from the Mew article Gear hobbing on the mill
and shows this test gear set of 1 module. A silver steel cutter is hobbed
whilst set over at 5 deg giving some clearance ,the cutter is set up
in the Dore westbury and cuts to the initial depth .From there on the
cnc control keeps the gear blank and cutter syncronised and the z axis
planes the gear form ,the cutter does not rotate but rolls around in the
internal gear form photo 4 .The rotary table moves about 2 deg and the
x y table movements move to these positions.
This gear set was only made to see if it could be done , sometimes it is
easier just to try these things to see how it works.

John

[Brian WoodParticipant @brianwood45127]

This is nice work John, it makes my efforts look rather trivial.

​I think you are right, it seems to be more a case of 'having a go' and learning from that to progress forward to the next version. From what I gleaned from reading, a little more space is needed to allow both gears to mesh nicely over a longer engagement and tooth tip rounding of the pinions can be made quite generous. That might explain Machinery's recommendation in using the #1 cutter to give the broadest base to the internal gear. The tips of the internal teeth are better for some rounding.

​Shapers have to be used for ring gears that are closed at one end, I can't think of another machine that would have the right sort of action for the job

​Andrew
​I am equally curious about the theory and may well order a copy of that book for my own interest. I am a dipper and browser by nature and like to have the information in book form without searching for it electronically. Thank you for sharing the reference. I find Abe Books quite helpful in stocking these older books.

​Brian

[Anonymous]

John: Thanks for the information and pictures, impressive. With the reciprocating hob do you 'rotate' the blank around a stationary hob or rotate the hob too? If the former I'd have no problem doing something similar. The question is what is the shape of the tooth on the reciprocating hob? For external gears it is a rack form, ie, straight edges. For an internal gear, where the shape to be cut has concave sides, I don't see how that would work? So presumably the hob for an internal gear is the reverse of one for external gears, and has the tooth shape for the smallest gear to be cut? Therein lies the nub, I'd have no problem cutting an internal gear, it's the shape of the cutter I'm not sure about. Of course if I needed to cut an internal gear I'm sure I could make a tool that would work. But since I have no pressing need to make an internal gear at the moment I might as well take the time to understand the design process.

I've found a PDF on the net which shows some of the calculations. It's in module rather than DP which I am more familiar with, but in essence it seems to be pretty simple. The desing process, not surprisingly I suppose, is very similar to that for an external gear. Basically the tooth shape is an involute from the base circle. It gives some inequalties which, if met, ensure no interference of the teeth. It also mentions corrected tooth shapes, but as seems to be common give no details of why that might be needed, or when to use it.

Andrew

[Mike LightfootParticipant @mikelightfoot72419]

My 10 M had it probably 20 years rescued from a scrap yard still scared of it!

[Ady1Participant @ady1]

My dad who worked at loads of engineering places in the Birmingham area in the 1950s tells me that it was a machine only the toolroom guys ever used

So mainly for repairing bits and making bespoke stuff

[IanTParticipant @iant]

That could describe a lot of my work Ady…

Regard,

IanT

[AjohnwParticipant @ajohnw51620]

Here's a real but small one for the courageous

**LINK**

I have a feeling laughingboy what ever will have to negotiate down from the bid price.

John

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