Member postings for John Hinkley

Chris,

Faced with a similar problem when I was building my original gearbox, I used a broach and home made broach bush. The first internal keyway was made in the normal manner and then the bush was rotated so that the formed keyway located in a second slot in the bush machined at the desired angular displacement from the first. The benefit of using a broach, of course, is that you get an even depth cut throughout the whole length of the workpiece. Downside is, they're blooming expensive! I can't take a photo of it without stripping the model down, but here's a screenshot of the CAD file of the broach bush:

In this instance it was to produce 6 equi-spaced keyways so each rotation was at 60° to the previous one.

I'm doing a similar thing for my latest gearbox, but that's all 3D printed so is just a matter of pressing a button a waiting a short while.

John

Edited By John Hinkley on 03/10/2023 09:15:27

Hello, Nigel,

Sign in to the site and then click on "Classifieds" on the black bar towards the top of the screen. That will take you to a new page where you will see the words "manage my ads" displayed at the right towards the top. Click on that link and you will be able to make the necessary changes.

John

As a relative newcomer to 3D printing, I am sticking for the moment to the filament supplied by my machine makers if only to remove one of the variables in the process until I gain more experience. I pay £22.99 for a 1kg roll of PLA. Only downside is the minimum order of £45 to qualify for free delivery from Bambu Lab. Other flavours are similarly priced and some are available without a spool though I don't know the price. Presumably cheaper. I have to say the quality appears to be very good, giving an excellent finish which exceeds my expectations for the machine.

My 2d,

John

Andrew Johnston, forum member, has, or at least had, a Britan repetition lathe. He may come along and offer some pearls of wisdom on the subject. I seem to recall that he used it to produce a number of fasteners for his traction engines, amongst other things.

John

I fitted two concentrically mounted LED angel eyes to my Warco VMC mill and would echo what has already been said. The I installed them (around the spindle) could give a bit of a shadow on the workpiece, depending on the distance of the light source from the workpiece. In practice, I very rarely used them, preferring to rely on the the bendy IKEA desk light I originally fitted.

There's a couple of photos in an album and a more comprehensive video on YouTube.

John

Can you confirm the type designation as "MF"? Mr Google has never heard of it. Is it the Warco Minor mill in your photo album?

John

Just to round this off and put it to bed, this is what the gearing/selector mechanisms looks like inside the case. Still missing are the gear selector forks - still to be drawn, but now that I've got the relative positions laid out, I can start on that.

The gear selector tracks were reasonably easy to set as I'd initially drawn them in 2D and measured the overall length. I then converted that from circumference to a diameter and rounded it up to the nearest convenient size. In this case it was 25mmØ.

Thanks, once again to all who contributed suggestions and especially to Jason for setting me off on a feasible solution.

John

Well, I've only gone and done it! Or rather, Jason showed me how and I implemented his suggestions.

I can use this part three times and connect them together with suitably sized shafts to make the selector barrel. I merely need to calculate the amount to rotate each consecutive drum to time the gear changes correctly. But not tonight! That's a job for another day.

Thanks to Jason, David, Ady.

John

Jason,

My page has just updated to show your 14.50 reply. That looks promising. I'll have to see what I can achieve in Atom.

John

Off to watch your video..........

Jason,

I THINK i understand what you're getting at, except for the straight bits.

I think i might try doing it piecemeal using revolve cuts in angular sections and then joining them with helical cuts as you suggested. Come to think of it, it would probably be easier to do that the other way around. I'll have a go later when my brain has cooled down and report back on my progress - or lack thereof.

John

David,

Yes. Me too. I can see how to do it in Alibre design but of course the wrap function is not available in Atom. Thanks for trying any way.

Back to the drawing screen for a re-think and maybe a modified design.

John

P.S. Can't figure out if it's possible in Fusion 360 either, if that's any consolation.

Thank you for your replies and hints.

David, the solution shown in your second response looks to be just the job. I'll try that after lunch as well as having a butcher's at the Framework link.

This is part of a Hewland FTR sequential gearbox selector barrel part 45 :

And this is what I've done on a plane surface by drawing the path and then the profile on the plane at right angles to the path followed by an extrude cut along said path.

Doesn't look too dissimilar to your example, David, so my hopes are high!

Ady 1. Yes, that is an assembly screen grab. I dread to think how long something of that complexity would take to print as one job, even with my high speed Bambu Lab X1 carbon printer! And just imagine the support structure that would be needed.

Regards, John

I am progressing albeit slowly with my design for a 5 - speed sequential gearbox and have got to the stage of trying to produce models for the gear selector drums, Now, here's my problem. I have sketched out the desired features for the selector forks to follow in 2D, by drawing a profile and using the sweep function. I cannot find a way to wrap the path around a cylinder so that the profile follows the desired pattern. Any ideas?

I've Googled and looked at the Atom forum but as soon as you type in "wrap" all it seems to come up with is to do with text.

I should add the I'm producing the resultant parts on my 3D printer which I'm slowly getting to grips with.

Here's what the design looks like so far :

John

Hello, Vic,

I'm afraid that I included the rotary broaching tool and all its other accessories in with the sale of my lathe a few weeks ago when I disposed of all the machines in my workshop. However, there is an album which gives a bit of information on its construction here should you want to view it. The design was based on the principles outlined by Mike Cox on his web site, though I altered it to suit the materials I had to hand in the scrap box. For example, I used a redundant revolving centre for the rotary broach part and selected various odd bits of assorted mild and silver steel for the rest. It was designed to accept 8mm diameter broaches which are available purchase commercially but I chose to make my own ('cos I'm a cheapskate). I also made a video of the broach which is here on YouTube. should you feel inclined to watch. The video was made after the broach was constructed so doesn't show much of the actual machining but I do try to explain the method.

John

Surely there's no need to go overboard on this? Just how much torque is a thumbscrew expected to apply? I would have thought that there was sufficient grip between the knurled part and the socket bolt by the application of Loctite or similar or press fit or even heat/freeze fit. But then, I've been wrong before and will, no doubt , be again.

Like Martin Kyte, above, I'd make it in one piece and then broach the socket afterwards if integrity is an issue.

John

The article to which this applies, on page 55, uses the form "radii" - so everyone should be satisfied.

John

Latin O level pass grade B

added smiley - don't know what it means, but intended to imply mischievousnesses.

Edited By John Hinkley on 17/09/2023 09:57:52

Simon,

I was interested in this addition, but Duncan's link didn't work for me. However, it gave a starting point for a bit of Googly detective work. There's World of Ward for starters and from Roy Vaughn's pointer you get to Thread to shoulder mod in James Clough's "issues" tab on github. The discussion progresses to stopping and starting threading. It sounds more complicated than it is, probably. Easier if you have the code installed and the display in front of you, I guess.

John

I fitted a 4Nm closed loop stepper motor to my lathe when I followed James Clough's series for adding an ELS. The closed loop stepper eliminated "lost" steps by virtue of some clever electronic wizardry and/or software manipulation of data which I can't pretend to understand. The setup never gave me a moment's trouble and as far as I know continues to give faultless service in its new owner's hands. Interested parties can waste lots of time by watching the ups and downs of the installation on YouTube.

The journey starts here.

There's quite a number of episodes and a lot is specific to my lathe so can easily be skipped through.

John

Edited to make it slightly less unreadable.

Edited By John Hinkley on 10/09/2023 10:01:19

Did a bit more digging and, as Howard says, Jacques Maurel produced a gesign for such an animal. It was apparently described in Engineering in Miniature (June 2016) as referenced in this thread on the mig-welding web site.

John

Graham Meek showed a photo of his blade tension setting device In this thread. I don't know if its construction is described in MEW or another publication; perhaps Graham will see this and point us in the right direction.

John