Member postings for brian jones 11

Indeed Pete I am rushing my calcs and must pay more attention

Yes Jason if you saw my rough attempt at a spiral chivved bolt, its a wonder I got anywhere near right ball park

but will try harder

Have any of you spotted the inherent fatal flaw in my conjecture yet?

JB no. of teeth issue

Q

Interesting that you seem to have about 47 teeth from a quick count up, with a 13tpi cutter and a 27.3mm dia blank I would have thought 42 teeth, so the method is very unreliable

UQ

Yes the theocratical number would be 42 for starting at 27,3mm dia allowing for pcd using a 13tpi thread

but what happened in practice for my brass blank is that some rolling took place and my OD increased to 28.07 gives predicted 45 teeth but I actually got 46

But my blanks are only 17p so a bit of trial and error may result in predictable repeatable results

Now this may improve when I use my proper cutter

Hold that thought

Well guys its all good input and shows we are addressing a serious issue - making spur gears

For this discussion I discount CNC and stepper motor drives as this is a different diocese IMHO

I also discount the lathe chivving method cos its not on msg and you can make up some complex jiggery to hack away - you cant buy one off the shelf btw

Ialso discount geared hobbers - the tools alone are £150 - thats all way too expensive

So this is for Doreen

We need to focus IMHO. Remind you of the SOW

A quick cheap way to make a serviceable spur gear from a non ferrous blank. It does not have to be perfect form, only for light load and speed. The issue of No. of teeth may not be so important if its only say within a few percent for some applications - especially model making as these are never put to live use (as admitted by one of our luminaries)

More work is in hand AWS as I improve my method of chivving bolts

None of the armchair pundits has spotted the limitation of this method - meh

Vouchsafe I may, but I have a cunning plan

OBTW to answer JBs question, yes it did take me ca 10+ mins, but I was cautious at my first attempt. I think I can up the spindle speed x2, and it will surely benefit when I make a properly made 6 slit bolt, not off and angle grinder in a vice jobbie. Work for 2mrw

Edited By brian jones 11 on 17/09/2021 01:55:41

Well PR post a pic of a hobbing attachment - not a specialised hobbing machine - that doesnt count, its not for the hobby machinist.

My point here as I expect you noticed is that we all take for granted that a lathe is generally designed to be able to make screw threads. Its no big deal

But a mill isnt set up to make gears in a similar way (nor a lathe for that matter)

In both cases you can go for a dividing head and laboriously rake out each tooth

I dont know of a simple system that allows you to cut gears with ease and speed (I am discounting the modern use of stepper motors for the job for the purposes of this discussion. No electronics allowable

You need to lock the spindle rotation with the gear blank rotation by suitable gear chain and the whole should run and chew out a gear - you may need some movement of the cross slide if its a thick blank of course

Thats hobbing on gas

So is there a ready made attachment for mill hobbing?

Hence my pursuit of a cheap charlie way of knock up spur gears - we already know the worm gear method

and this is an expansion of this method

Well MG - think out of the box

if that cog was 10x dia then its a spur gear, just shunt the tap across the z axis, not so easy on a lathe without a vertical slide - but doable

innit?

obtw you would have to tilt the axis to match the helix angle to get orthogonal teeth as JB has pointed out before

Edited By brian jones 11 on 15/09/2021 21:02:56

And for the record

this is what real hobbers use, who has those attachments?

And Im not the only one with a perverted interest in rough gears

A senior luminary on this VERY board was caught doing this a few years ago

As I am sure you are all on the edge of your seats (not possible for sunken armchairs) here's my first attempt at a brass gear

I keep forgetting to landscape my phone, notice a cheapo brass blank - 17p whats not to like

before you all leap from your electrically assisted orthopaedic memory padded comfort

YES its not perfect, there are flaws but I put that down to the rough way I chivved up my spirally sliced bolt on my vice with an angle grinder, lots wrong with that method

I have a cunning plan to make better cutting tools from bolts the proper way

More work needed

Who or what is Doreen?

A Dore Westbury vertical mill, as classic as the Myford (Maureen) is to a turner

they are both temperamental wimin who dont like being neglected

Edited By brian jones 11 on 14/09/2021 19:00:48

http://www.lathes.co.uk/dore-westbury/

Edited By brian jones 11 on 14/09/2021 19:21:48

When I woke up from my pantograph AO drawing board this am, I was seized with a new direction . Why not try

straight slits down a bolt thread. My angle grinder disc is 1mm thick, so I made 5 axial slits coinciding with the hex head - in a heartbeat. If the gear blank is say minimum 3mm - mine was 6mm, then the cutter shouldnt come un meshed.

So this is the result

This is during the rolling and polishing process

This was just a quick try with my grinder, slitting along 6 edges to match the Hex head, done by hand so a bit naff, could do better

Not a chip in sight all round and SHOCK 74 teeth (not 73 predicted) -well it wouldnt suit a clock maker

Im not skilled in taking close ups. the gear is mucky from the brasso fluid which I applied to polish it up to please the Grommets

As you seen its a presentable form, even with rounded tips and roots?

I polished it up by using a plain bolt without cutting edges and some Brasso. I think the applied rolling pressure helped (after all they make quality precision threads by rolling process)

So even if it fails on soft metal, it can produce respectable plastic gears quickly and cheaply without complicated attachments, universal dividing head and loads of patience etc

I have some AL and brass blanks on order

Maybe look up some larger thread - 2" bsw 4.5 tpi that should knock the stuffing out of sofa dwellers

JB you were on track and then spotted this was not the proper way, dont attack from the side as the tap doesnt have space to mesh properly at first with the blank. You quickly retrenched and attacked from the middle inwards (as they do with making a worm). It righted itself and you proceed full sail to finish. The damaged teeth were a periferal result left over from your first attempt - trivially observed by the old SOD not paying attention from his armchair.

Now your first result you reckoned you made a nice knurl but you were only using 1/4 BSF 26tpi

Now I am using 1/2" UNC 13tpi so my pitch is ca 2mm and produces a more credible size gear

BUT spiral flute taps are rare on EB and larger ones get very expensive, so not a practical direction I admit

I had a cunning plan and Ive had more results from Doreen see below

Regular hobs have triangular teeth and generate involute forms

I didnt know that?

But look at the method

if i want two gears say 2:1 ratio, stick the blanks of 2:1 OD in your jig and 5 mins later ish you got a result

no fancy hobber linked to spindle ££££, just slice up an HT bolt to suit blank OD/pitch = teeth minus 1

Cheap and cheerful for non ferrous mtl

Well well Mel the Magnificent confounds his armchair grumps, Stand back from success

I was backward in forthcoming as I didnt have any suitable blanks and ordered from EB

the pix are turned cw cos i forgot to landscape my phone - as you do

These are simple acrylic discs 6mm x 45mm gives circum = 141mm

i got 71 teeth

the bolt was 1/2" unc give 13 tpi - 1.954mm pitch so should give 72 teeth

so you get 1 less

Also note that my teeth are slightly slanted as I didnt bother with the helix angle just now

Note the crude bolt with the slits cut at 45deg, 6 in all to match the bolt head which i sliced off later. As a cutter it worked really well for what it was. I was very surprised. Even under a loup the teeth were respectable

I will have to try it in Aluminium and Brass before the naysayers go ape and spit the dummy

I will also try factoring the OD 71/72 x 45 = 44.37mm

Maybe try a slant of the blank to make a helix

I also located a pair of RH - LH threads might go for a herribone

I did make a video but I dont know yet how to put this on YT as per JB. Its so quiet and unhurried I shall add something symphonic

Edited By brian jones 11 on 13/09/2021 19:30:54

well I did manage a vid on YT

https://youtu.be/rcXPWMTVNig

its a lot easier than it used to be, i remember a daunting process which deterred me

Sorry no happy housewife muzak, this is my first YT attempt, lots of mistakes but I hope it shows the method

have ordered some al and br blanks and also the means for my herribone rude attempt. Who knows, will this lead to a rough hyperthyroid crown and pinion gear set. get your pooh sticks ready.

Edited By brian jones 11 on 13/09/2021 20:30:38

How many teeth did you end up with JB? 59?

What happens if you tilt the work at 45deg to a straight flute tap? - yes you will get a helical gear but does it work?

I am assembling my stuff on Doreen AWS going straight for the sliced bolt

Eureka tool vid

https://www.youtube.com/watch?v=F_w92CEMlT4

If thats what floats your boat?

correction

the method never caught on because it wont work with straight flutes,

It works for worms but I meant NOT for spur gears

Edited By brian jones 11 on 13/09/2021 13:27:56

Mountebank Millionaire Mel Maverick here with the magnificent flying Myfords, star of the silver suds tray and adored by lady lathe turners

That boy Pike is one stoopid mudder

Q

• Cannot guarantee how many teeth will be be cut on a blank. No good for applications requiring fixed gear ratios.

Doesnt matter, I got 59 when I aimed for 60, but my model will still work

• The teeth are an unknown profile, neither hypo-cycloid or involute. So whatever the profile is, no good for low friction, power transfer, or low noise applications.

Going thyroid was never the intention

• Difficult to make two gears that will mesh together from fixed centres.

Drill your centers afterwards

• Can the same cutter be used to make both gears,

Yes anything from ca 12? teeth upwards whats not to like

• or not? If two different cutters are needed, what are the design parameters? I don't think anyone knows.

parameters shmarameters just suck it and see - like all talented bodgers. FYI they fixed a leak in the ISS space station with chewing gum or blutack?

• Difficult to make a replacement gear for an existing gearbox.

So go the traditional route may you live so long

UQ

Can you hear the silent roar of thunderous hooves all rushing to EB to sources spiral flute taps meh

BFN I must go and see my Doreen and make swarf - how bad can it get

OBTW

this approach is far from new, and there are good reasons why it's never caught on

the method never caught on because it wont work with straight flutes, but then came JB and his spiral flute

ROTFLOL

Edited By brian jones 11 on 13/09/2021 12:35:04

Well if you havent got a proper hobber you can always go for a dividing plate and cut the individual teeth , its what proper modellers do innit, probably take all morning.

Ive watched that vid several times (is this like machinists prawn?)

would like to see another go with something to blow away the swarf so we can get close to the dirt - fascinating.

Others wading in this mucky subject have reported that they seem to get less teeth than was calculated given OD x tpi

So yours in 3.14" x 19 (1/4bsf) = 60 teeth

how many teeth did you actually get JB?

Fantastico JB whats not to like?

so make another gear and see how they run together

you can smooth them out by running them through a shallow bath of fine abrasive powder of some sort

Its exactly what I intended to do

Obtw

the ultimate insult to the purists is to use my sliced bolt method, ie take a CS HT bolt , hold it in a vice and use an angle grinder with 2mm blade to make 30 deg slices longitudinally across the thread, rotate at 90 deg and repeat

then you have an approx to a spiral flute cutter

That was to be my last ditch attempt cos spiral flute taps are not easy to come by and are v expensive if large say 1"

So it may not be a nasty knurl at all, just a rough fix for those without expensive complex gear hobbers who need to knock up some gears for lightweight use.

I didnt have time today but your vid has really kicked my butt

I hope other members appreciate this

Indeed JB there are always many ways to skin a cat in geometrical drg

the cup was simple to show that zero thickness shape dont work in 3D

course I may be prating from my freckle as there;s something called surfaces lurking in my tab bar

thats the trouble with solo on line learning much of the dubious tutorials are outdated and things change

if you are in a design office you get the latest buzz

OBTW JB I have received some gear blanks which I will try out AWS

Yes its like ballet innit

is that intersection point accurate

can you draw 3 lines to intersect

are all the edges the same length to n dp

if so thats cooking on gas

Edited By brian jones 11 on 11/09/2021 20:06:30

you see i am doing my homework

I constructed my solid using lines not a glitzy extension.  SU2021 has addressed the intersection problem and it will now intersect in 3D space correctly, but I have yet to xlate this into an SE experience

FYI I booted up an old copy of Acad 2009 (last time I used it) which I still had on my trusty Acer aspire one notebook, still going strong after 15 years being toted around the world - its my repository of old XP sp3 progs that still have value

I note that this ver of Acad didnt handle circle intersects accurately.  it gave an approxinate point in 2D but if you zoomed in closely you would see that point did not coincide with the circle intersection.  I seemed to remember that I had to make a manual calc to get this accurate.

most of the time you worked in 2 or 3dp for eng purposes so it only affected the lsd and I only did construction stuff

such imprecision cant be tolerated in 3D geometry now

This may seem pedantic to 2D guys but 3D teaches you to be precise or suffer down the line

In those earlier days it was always said that customers were not willing to pay for the considerable extra time needed for 3D drafting.  The offshore industry had to take it seriously when designing modular packages to be craned onto platforms and had to fit together perfectly.  The interior space of these modules was highly constrained and had to accommodate fixtures from piping, electrical, instruments and vendor packages

You can imagine squeezing all those different discipline products into say a container box, plus room for human access and maintenance.  I guess an engine fitted into a modern car bay presents much the same challenge,  Before 3D Cad appeared we made plastic scale models in the DO. They were expensive in time and materials for scaled piping components, valves, fittings, gauges, cable trays etc - maybe 1000+ different pieces

Today 3D Cad is indispensable for many manufacturing and construction industries plus its interface with CAM and all the data produced for BOM, parts lists, assy, procurement schedules etc.

A far cry from the rather haphazard seat-of-the-pants way we ran construction projects back then (pre-windows btw)

I read recently that Tesla's model Y has a complete die cast aluminium chassis. This is huge and a remarkable achievement for which Tesla is leading the world

https://www.foundrymag.com/molds-cores/media-gallery/21932049/tesla-is-turning-to-diecasting-in-a-big-way

Now thats 3D designing

Edited By brian jones 11 on 12/09/2021 18:10:56

Well JB a lot of contributors are missing the point - perhaps the reference to balls clouded their vision

You see the derided 2D compass was the way to find an intersection in 2D

But take the tetrahedron , we have a base triangle and a point in space to draw 3 identical side lines to meet the others from their respective vertices.

obvious - have we lost them yet?

a compass will describe a sphere in 3D. So we are intersecting 3 spheres (which will give 2 points +/- Z)

BUT the CAD circle is approximated by a polygon (default 24,36 segments)

Without using built-in tools as may exist in some CAD apps, it is difficult to intersect 2 circles on the 2D plane - it wont give you an intersection point. In SE you have to use the Trim tool to remove the outer arcs leaving you with a lens

This lens will be given intersection points vertices you can use and its accurate (to 6dp)

Now there are glitzy tools in some CAD apps that will draw platonic solids ready made which skates over the fundamental issue here - your vertices must be 100% accurate (near enough is not good enough - which you can fudge in 2D). More than 3 must be coplanar or they wont make a face - plus the other manifold rules

to construct the tetrahedron with a given construction line drawn from centre up the Z axis, Can you draw a line from one of the vertices with the given side length so that it intersects with this Z line

If you can you cracked it.

I read that SE cant do 3D sketching whereas sketchworks can but yet I see a tab on the SE worksheet that says "3D sketch"

As Im still on the 2D plane I was afraid to open it but this has now confused me

Also a quickie?

When I open SE it defaults to Synchronous - should a noob be starting out with "Ordered" modeling ?

I hope these discussions will help other noobs because, as has been noted, the industry is utterly overpowered with confusing hype making the learning curve much more difficult than it needs to be - wading thru their rubbish - i remember Acad ws just as bad way back - telling you how wonderful it was and what you will learn without actually teaching you.