cutting spur gears on a mill

[JasonBModerator @jasonb]

I love than for their intended purpose

As a couple of other posters have already stated they are likely to make better hobs than a standard tap as there should always be part of the tap in the cut so the free hobbing will be less likely to get out of phase.

[DiogenesIIParticipant @diogenesii]

..we'll be expecting to see a shot like this at the end of this thread..

 

Edited By DiogenesII on 23/08/2021 20:57:53

[Anonymous]

Posted by JasonB on 23/08/2021 20:45:40:

….they are likely to make better hobs than a standard tap…..

Specifically spiral flute, as opposed to spiral point.

Andrew

[brian jones 11Participant @brianjones11]

Yes working on it but its straining my cad app (sketchup – it was originally for the architectural artists impression market and was never intended for engineering but the user fan club took to it and developed it in remarkable ways – Ive been a fan since 2004 )

which cad app do you use.

[JasonBModerator @jasonb]

I use Alibre and a bit of Fusion360

[brian jones 11Participant @brianjones11]

Posted by JasonB on 24/08/2021 16:49:51:

I use Alibre and a bit of Fusion360

New to me

OMG did you pay £1200 for a one year licence?

Is it one of those full cad/cam packages to CNC?

Looks like youd spend a year learning it before cutting metal

Edited By brian jones 11 on 24/08/2021 18:19:37

[Nick WheelerParticipant @nickwheeler]

Posted by brian jones 11 on 24/08/2021 18:16:33:

Posted by JasonB on 24/08/2021 16:49:51:

I use Alibre and a bit of Fusion360

New to me

OMG did you pay £1200 for a one year licence?

Is it one of those full cad/cam packages to CNC?

Looks like you'd spend a year learning it before cutting metal

The free version of Fusion has a few annoying restrictions, but nothing too bad especially for a beginner. The worst ones are only 10 working documents at a time, and not being able to edit external documents. It's easier to keep all the components in one document, so that doesn't affect me much. I don't use the drawing part very much, so it hasn't annoyed me enough to pay a subscription.

These programs all work in similar ways, but with a slightly varied focus.

[JasonBModerator @jasonb]

Posted by brian jones 11 on 24/08/2021 18:16:33:

Posted by JasonB on 24/08/2021 16:49:51:

I use Alibre and a bit of Fusion360

New to me

OMG did you pay £1200 for a one year licence?

Is it one of those full cad/cam packages to CNC?

Looks like youd spend a year learning it before cutting metal

I have Alibre Pro and pay the yearly fee which is about £300 that is just CAD Licence was bought long ago with their entry level version which I ran as a one off payment ( approx £150) for several years.

I use the free version of F360 for CAM and have not found it too restrictive compared with the paid version which I did have free access to up until about 6 months ago.

[brian jones 11Participant @brianjones11]

OMG the dreaded AutoCAD outfit. I was on that for many years, only 2d mostly schematic, I did dabble with their attempt at 3D, what a dogs breakfast that was.

Auto desk was a huge package with specialist modules for Pipers, Civil, architect etc. They quickly put themselves out of reach of hobby market – big mistake.

Then I discovered Sketchup and the 3D world transformed, I was able to pick up the intuitive basics in half hour – course it takes much longer to get real skill but its a gentle learning curve andf some excellent vid tuts as well

and its FREE for home hobby use

good for quick sketches

no CAD CAM i/f

not trying to sell it btw, its just a wonderful simple tool

I presume you have access to a vast library of models and put your display up in 10 mins

good fun though

[JasonBModerator @jasonb]

Although it is possible to import many "stock" items I seldom do as most of what I make and draw are not stocked, certainly hard to find parts for steam engines from commercial suppliers these days.

Have a look at the sketches I just poste din the Hoglet thread, I could have gone looking for the oilite bearings, sprag clutch and a spur gear but quicker to draw them though I did use a gear generating script for the spur gear.

For engineering I would say Alibre and F360 would pee all over sketchup, couple I drew earlier and then built

 

Edited By JasonB on 24/08/2021 20:50:56

Edited By JasonB on 24/08/2021 20:56:59

[brian jones 11Participant @brianjones11]

Indeed classy visualisations

How easy is it to keep these linked to dimensioned engineering drgs – separate pages/tabs?

I would have expected an Autodesk product to have libraries of std parts eg a screwed rod, spur gear nut and bolt etc like the piping module in Acad, had thousands of piping fittings ready made to plug into isos to check for clashes etc and make 3d models (like we did for offshore packages etc)

but thats a long way from hobby work

I had such a bad experience with Acad 3D that I never went back there again, It took a long time for Acad to wake up to the windows platform. for a long time it was very clunky. Mostly I stuck with 2D schematics and layouts

3D work initially was a lot more manhours and clients didnt want to pay for visuals, till offshore packages in confined cubicles made it an essential tool – basic not pretty like your models. But it all linked back to 2d drawing spaces

Moved a component in a 3D model and its position was translated to 2D drgs – big time saver

Happy days, big money back then

Its all done by Flipflop sweatshops now – they had a natural ability with CAD.

In SU you only get one view space but you make components and hide them, easy to lose track so only for simple geometric modelling, but artists make great visuals of amazing complexity like cars

https://www.google.com/search?q=sketchup+cars&tbm=isch&ved=2ahUKEwj46q-vxMzyAhWnwQIHHfcMBVgQ_AUoAXoECAEQAw#imgrc=Qy-7J7cuVbgbnM

[JasonBModerator @jasonb]

Posted by brian jones 11 on 25/08/2021 16:56:47:

How easy is it to keep these linked to dimensioned engineering drgs – separate pages/tabs?

It's fully parametric so any change to an individual component or the assembly will automatically be done on the 2D drawings, bill of materials etc.

I think you do get the libraries on the paid for version of F360 but the free one has easy access to companies like McMaster Carr so you can just drop in a CAD model of any of their products

[brian jones 11Participant @brianjones11]

Hi JB I am still beavering away on hobbing but ran into major probs with SU and trying to intersect and cut a slanted cylinder from a screwed rod

Can your system model a spiral flute tap easily?. I am getting there and got a method from another board but its been fraught

I am looking at knocking up a manual hobber arrangement turning the tap by hand or with a 12v motor froma window winder (£10 bargain 30rpm 20W bags of torque). I have a speed controller as well

I also though of adapting a HT set screw by grinding a diagonal slot down the shank. It is an old trick to knock up a repair tap for female threads. The slot should make cutting edges sufficient for soft material, eg AL brass. delrin, tufnol – difficult expensive to get spiral flute taps

A simple hand jig might just suit small gears for light duty

I found some LH threads so might go for the herribone

It all makes work for lockdown man

The betting is that we will all get delta covid by xmas so i better get a wiggle on

[JasonBModerator @jasonb]

Posted by brian jones 11 on 30/08/2021 19:02:47:

Can your system model a spiral flute tap easily?.

Yes thanks, its no different to modelling the helix of the tap, just a different profile and a steeper helix and multi start. Quick one here though flute profile is not right, would need to go and have a better look at one in the workshop.

[brian jones 11Participant @brianjones11]

Yes thats the idea i had for a HT bolt

Now you need to interact that with a gear blank and see if it rotates without clashing

 

OMG I havent got that far yet using SU.

 

perhaps i should stop wasting time on CAD and get on with a lash up jig to prove the concept

you have shown the way

cheers

 

Edited By brian jones 11 on 31/08/2021 02:21:38

[brian jones 11Participant @brianjones11]

Well I went from lockdown to near break down now I had a break through

It was quite a business but I had some kind help from the SU forum that taught me a lot i didnt know and also some very neat extensions (all so far free)

not a good pic but now I have to create the gear blank

[brian jones 11Participant @brianjones11]

Well you can have too much of a good thing and I have push my cad model as far as I need to go (having mastered the art of boolean intersections)

spiral flute tap method

a slightly dodgy gear form as all the armchair pundits predicted

I will now proceed to make physical models to see if I can get usable rough gears

I will also try slicing an HT bolt to mimic a spiral flute, I wonder if case hardening might help, but I only expect to cut AL brass SRBP delrin = well it worked for millions of mechano sets but thats not real modelling here.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by brian jones 11 on 02/09/2021 06:29:47:

[…]

well it worked for millions of mechano sets but thats not real modelling here.

 

.

You might like to browse through these, Brian :

https://www.meccanoindex.co.uk/Drawings/Index.php

When I last looked, I’m pretty sure there were several gear drawings which called-up special hobs.

MichaelG.

Edited By Michael Gilligan on 02/09/2021 12:49:40

[JasonBModerator @jasonb]

As per the link I posted early on in the thread you can even make the hobibng machine from Meccano here

[brian jones 11Participant @brianjones11]

Wow MG what a fantastic treasure trove. I see that meccano has morphed into an instant bolt it together ready made model type of kit. Instant gratification, no thinking or skill required – bit like CNC is to Myford.

Its old frats like us who harp on about classics, eg austin 7, monopoly, meccano, Myford, hornsby etc

Looking at those old drgs reminds me of my early years in the drg office and the holy terror chief draftsman

A lot of skill was required to produce even the simplest production drg. Draffies lived in mortal fear of making a mistake with dimensions, tolerances, surface finish. This took its tool on health. Always a pressure on speed vs accuracy. Knock up a drg and we will see if it fits when we make it. Imagine the shame when you got a size wrong.

[brian jones 11Participant @brianjones11]

Posted by JasonB on 02/09/2021 13:17:54:

As per the link I posted early on in the thread you can even make the hobibng machine from Meccano here

Well stap me vitals Monsignor – if that cattlewaggler isnt using a parallel flute tap to cut a spur gear

Its not free hobbing though

But as I intimated above, that level of meccano use required considerable thinking skills, no instant gratification there.

[brian jones 11Participant @brianjones11]

Well JB consider me suitably chastised. Having dipped my toe into the world of 3D printing – what a lot of hype here and worse still the market is flooded with cloned Prusa'a what a travesty (and a serious waste of time and money for hapless buyers IMHO) Yet serious printing has its place but what the hypers are coy about is that models can take hours, days, weeks to complete and if you didnt think that was bad enough, your CAD design could have hidden flaws xmitted to the STL file which is where Sketchup fails badly. Your print may likely show up after hours of toil to have a fatal error that makes your model into trash (and be sure not to have a power failure during that time or run out of fibre)

Because of its Architect origins for quick visualisations it compromises significantly on geometrical correctness and produces all manner of non manifold bodies because it allows you to break all the dozen rules for creating regular solids and in a manner that is hidden, obscure and difficult if not impossible to cure.

I find it utterly shameless that SU is touted as a suitable designer for the 3D world (just cos its easy to use)

My spiral flute tap above would probably be impossible to convert into a regular manifold and print in 3D

IMHO just dont go there

So following JB wise words I am floating along the lockdown path of Fusion 360. It will takes 100's hours study I dont doubt but opinion is that Solidworks would be 10x that learning curve and is meant for serious manufacturing assy

It occurs to me that I should now be moving over to CAD and Tech drg topic with my new direction – make it so.

But I have a couple of trials with spiral taps to complete this topic, which if nothing else has made me come to know how little I know

[lee websterParticipant @leewebster72680]

Sketchup is good fer what it's good fer. Creating slightly cartoonish drawings that dont have much in the way of chamfer or fillet. I have designed many things with good 'ol SU, but I wouldn't use it for cad work. If I could afford it I would use Solidworks. I can't so I don't. I spent a year or two learning Freecad. Don't go down that route. F360 lost my respect long ago. If you want to be one of their unpaid testers using hobbled software, go for it. But before you do, try DesignSpark mechanical. You can't produce technical drawings with it, but seeing as I can't read 'em I don't need 'em. Designspark has been an eye-opener for me. It has limitations, but I can live with those. And it's free. My fave word.

Lee

[Pete RimmerParticipant @peterimmer30576]

https://www.thingiverse.com/thing:4043256

Drawn with Sketchup.

[JasonBModerator @jasonb]

well curiosity got the better of me so I dug out a 1/4" BSP spiral flute tap as it was my largest spiral flute one, worked ot the helix angle at the pitch diameter to be quite close to 2deg so held a collet block at that angle in the vice. into that went an arbor from previous gear cutting jobs to hold a quickly knocked up 1" dia x 1/4" thick aluminium blank retained buy an almost done up M6 nylock.

I tried coming at it from the end as you would using an involute gear cutter but thought it was not right as blank seemed to be rotating very slowly so tried again coming at it from the side them moving the work left and right.

Thinking about it afterwards the blank will turn slowly as there are about 60 teeth so at my 600rpm spindle speed the blank is only doing 10rpm, this means you need a very slow feed across the blank so it's not really a quick method.

Well I'd say it's passable if you wanted a straight knurl and did not have suitable wheels, but I don't think I will be using the method any time soon for gears.

Rough and ready video

 

Now lets see yours Brian

 

Edited By JasonB on 12/09/2021 19:31:22

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