Spiral bevel gears n gearing

[ajoeiam]

Greetings

Not to be contentious - - - but - - - - anyone out there ever tried to DIY some?

(yes - - - I mean spiral bevel and not bevel nor miter !!)

Thinking with a slotter or decent sized shaper one could possibly with some added tools/connections.

What say you?

(Dunno if I stuck this topic in the ''best' space. If there is a better forum - - please do advise!!)

 

[GreenTwin]

I have no doublt there is someone here who could rig up an assembly to cut a spiraled beveled gear.
Not sure if a straight cutter could be used on it or not, but I have seen an arrangement to cut a helical gear with a standard cutter, and so perhaps it could be done.

.

 

[gbritnell]

The only one I know that ever attempted and completed them was Lou Chenot for the Duesenberg model car. In conversation with him he told me how he did it but said that for all the work it really wasn't worth it. His gears were actually of the hypoid type, which would make them spiral bevel offset gears.

 

[SmithDoor]

They on a gear cutter just for spiral bevel gears. It can be done on Bridge Port mill.
I found it was simpler just buy made.

Dave

The only one I know that ever attempted and completed them was Lou Chenot for the Duesenberg model car. In conversation with him he told me how he did it but said that for all the work it really wasn't worth it. His gears were actually of the hypoid type, which would make them spiral bevel offset gears.

 

[Poppy Ott]

Is your query just a hypothetical or do your have a specific need? If the latter, and if skew bevel gearing would do, Kokomo Hiraoka provided very detailed instruction on making skew beveled gears in the making of his Climax engine.

 

[ajoeiam]

Is your query just a hypothetical or do your have a specific need? If the latter, and if skew bevel gearing would do, Kokomo Hiraoka provided very detailed instruction on making skew beveled gears in the making of his Climax engine.

1. Somewhat of both
2. went looking - - - - one 'may' be able to find the issues but the book seems to be unobtanium at the moment.

I generally have too many ideas burning in my bonnet.
Reading about the software used on 5 axis machines to fab spiral bevel gearing is part of the impetus as well.

 

[Poppy Ott]

1. Somewhat of both
2. went looking - - - - one 'may' be able to find the issues but the book seems to be unobtanium at the moment.

I generally have too many ideas burning in my bonnet.
Reading about the software used on 5 axis machines to fab spiral bevel gearing is part of the impetus as well.

If you want copies of the relevant pages, message me.

 

[mrehmus]

Alan Suttie made gears on his lathe using fixtures he built to hold the gear blanks. Fortunately he shared that article with me in issue#16 of Model Engine Builder magazine. As he mentioned, it took longer to make the fixtures than to cut the gears.

 

[Steamchick]

Thanks Dave: (post #4). I have struggled to find what I want in any catalogues on line... just specialists who make for thousands of £s. Does anyone have a source for small spiral bevel gears?

 

[GreenTwin]

McMaster Carr sells them, but probably not as small as is required.
They do often have 3D models of their gears, and you can actually download the gears in 3D, and 3D print them at any scale.
You could even 3D print them with Polycast filament, burn out the filament, do an investment casting, and have a working set of gears any size.

 

[abby]

Even making correctly shaped straight bevel gears is not so easy.
If you have a 3D CAD package you could perhaps produce a drawing and STL file of your gear requirements, if the gears are small there are several firms in the UK that could print your gear in wax at a reasonable price for use as an investment pattern. Jewellery manufacturers in particular could do this and dental laboratories will sometimes cast small parts in chrome steel if you talk nicely to them
You could get them printed in metal but this is expensive and I don't know how accurate they might be.
Just some ideas .......don't know how practical they might be.
Dan.

 

[mrehmus]

Even making correctly shaped straight bevel gears is not so easy.
If you have a 3D CAD package you could perhaps produce a drawing and STL file of your gear requirements, if the gears are small there are several firms in the UK that could print your gear in wax at a reasonable price for use as an investment pattern. Jewellery manufacturers in particular could do this and dental laboratories will sometimes cast small parts in chrome steel if you talk nicely to them
You could get them printed in metal but this is expensive and I don't know how accurate they might be.
Just some ideas .......don't know how practical they might be.
Dan.

3D printed gears of this style still have to be machined in almost all cases.

 

[abby]

I agree that machined finish is prefered , even commercial manufacturers of spiral bevel gears have difficulty with a ground finish but I assumed that we are talking model size and reproducing the appearance rather than the performance.
investment cast gears do work and can be improved by running a pair in together with fine grinding paste.Wax printers designed for printing jewellery patterns are far superior to the hobby printers , as you would expect from a Solidscape wax printer costing more than $55 K.
Dan.

 

[mrehmus]

I agree that machined finish is prefered , even commercial manufacturers of spiral bevel gears have difficulty with a ground finish but I assumed that we are talking model size and reproducing the appearance rather than the performance.
investment cast gears do work and can be improved by running a pair in together with fine grinding paste.Wax printers designed for printing jewellery patterns are far superior to the hobby printers , as you would expect from a Solidscape wax printer costing more than $55 K.
Dan.

Well yes, but as soon as you start talking about lost wax printing, you have left behind the direct 3D printing of metals. Most of the model engine builders I know want a good-running engine that will last. So yes, machined or investment cast will work well but directly printed metal components, in the case of gears, need machining to be acceptable.

 

[gbritnell]

Why is imperative to make this type of gear? As was mentioned youcould use a combination of the Chuck Fellows fixture and then make the same compensations as when making standard miter or bevel gears. This would be a ton of work for just a couple of gears.

 

[abby]

mrehmus
Just to make a point I said in my first reply to this post that it might be possible to get a gear pattern printed in wax , possibly by a jeweller.
Having run my own lost wax buisness for over 25 years I feel somewhat qualified to say this.
I went on to say that it might be possible to get a metal gear printed but at what ? accuracy.
If you feel the need to comment on someone's reply please read carefully what they have said first , this will avoid any later misunderstanding.
Dan

 

[GreenTwin]

I plan to cast these gears using resin-bound sand, and heat the hardened mold just enought to make the 3D printed plastic gears soft enough to remove from the mold.
I think it will work. Fingers crossed.
With a ceramic mold coat, I can get a smooth shiny surface finish, so I think with a little lapping, the gears will be usable.
Resin-bound sand is dimensionally stable, and hardens around a pattern just as if you were dipping it using a ceramic dipping/coating process.

.

 

[GreenTwin]

mrehmus
Just to make a point I said in my first reply to this post that it might be possible to get a gear pattern printed in wax , possibly by a jeweller.
Having run my own lost wax buisness for over 25 years I feel somewhat qualified to say this.
I went on to say that it might be possible to get a metal gear printed but at what ? accuracy.
If you feel the need to comment on someone's reply please read carefully what they have said first , this will avoid any later misunderstanding.
Dan

I missed that point when I hastily read your post the first time, but that is a good point for sure.
Glad to understand it now.
.

 

[MRA]

I wonder if this method could be adapted - using a lathe as a shaper. In contrast to the video below, the blank would have to be mounted at an angle (with an offset tailstock, or perhaps by mounting a tailstock centre in a boring head fitted to the tailstock, to enable it to be set across to the required taper - an idea I read recently in an old book which I rather like). But maybe the tapers required are rather extreme, and this would not work.

 

[JLaning427]

With a ceramic mold coat, I can get a smooth shiny surface finish, so I think with a little lapping, the gears will be usable.
Resin-bound sand is dimensionally stable, and hardens around a pattern just as if you were dipping it using a ceramic dipping/coating process.

I don't know all that much about casting. But I do know that all metals we typically cast shrink when they cool. Or at least I think that is correct.

I am curious how you plan to account for shrinkage, so you end up with a uniform, concentric, usable product that is of the desired size so it mates with the other gear? Is it just a matter of pattern and sprue orientation?

James