How to make mini camshaft?

[ZAPJACKParticipant @zapjack]

Hello,

i’m looking for a solution to make camshaft. Mini size, shaft of 4mm and Cam of 6mm high.

Is there any small grinding machine “home made” or other possibilities

Thanks for help

LeZap

[JasonBModerator @jasonb]

Do you have a milling machine? That would produce a cam in a couple of different ways

[bernard towersParticipant @bernardtowers37738]

EIM magazine 2003 for a cam copier attachment or westbury’s jig.

[ZAPJACKParticipant @zapjack]

I have a Schaublin 13 as milling machine and a Schaublin 102 N-VM as lathe.

But, I’m looking for a self made grinding machine.

i don’t have EIM 2003.

Regards

LeZap

[DiogenesParticipant @diogenes]

As Jason says there is a method of generating a cam profile by milling a series flats around an indexed blank. Blend with Swiss file and harden.

There are links and information here;

https://www.model-engineer.co.uk/forums/topic/how-to-use-camcalc-for-cutting-camshafts/

I hope some of this information will be useful even if you choose to grind the cams.

[ZAPJACKParticipant @zapjack]

Yes, thanks for the link.

But I work 100% “old fashion”

With other words, no CNC, no computerized assistance.

It seems that there is a method on lathe?

LeZap

[David George 1Participant @davidgeorge1]

I made a cam grinder made from three pieces of angle steel welded to a piece of bar for a pivot. This was attached to a base with two small uprights  with a hole through so that the first piece  pivoted forward and back. This was spring loaded forward with spring around the pivot bar. a couple of centers were welded onto the tops of the two arms one fixed for the center of the camshaft and the other a nut welded a threaded center the clamp the camshaft with a locknut to allow it to rotate. A cam shape was cut to the shape I wanted which had a hole through to fit camshaft diamiter and grub screw to adjust position of cam shape to.  A piece of angle was welded to the base so that the cam shape pressed against so the upright in and out when rotated by hand. After dressing the bench grinder wheel flat the cam grinder was screwed to the bench and ground many cams for motorcycles giving more lift and profile shape change mainly Triumph and BSA twins. I did another for Honda cam shafts but a lot longer but same basic idea.

David

[ChrisLHParticipant @chrislh]

Zap,

I have made a 2 cylinder camshaft for Westbury’s Wallaby engine design using the method described in the associated Model Engineer article. It worked out OK in the engine but I never had the courage to harden it, I worried about distortion. I can email you copies of the article if you are interested and send me a PM.

[Martin ConnellyParticipant @martinconnelly55370]

Are you proposing a circular cam profile because that is what will be produced on a basic lathe? This is a bit like the eccentrics used for steam engine valve operation in a lot of models. If so then one way is to use a 4 jaw chuck to offset the camshaft. For such small sizes it may be hard to be accurate. If you do not want a circular profile then some of the eccentric disc can be filed away afterwards.

Joe Pie did a video called “Turning a 1 Piece Miniature Crankshaft….This one is pretty cool” on Youtube that may be of interest to you for ideas.

Martin C

[Graham MeekParticipant @grahammeek88282]

Some years ago I made ETW’s Seagull engine, but with a few modifications.

The camshaft for this engine was made with separate cams which were hardened and fitted to a Silver Steel shaft.

The cams are easy to make this way and follow ETW’s contours.

This design was later used in another engine which as yet has not been finished, but the camshaft for this was 3 mm silver steel. Half the size of the original above.

I did write an article on this called “Cams Made Easy” which was published in EiM.

This method removes any chance of distortion and the cams can be ground on the flanks with a simple toolpost grinder.

This is the camshaft for a Vee Twin built by the late Dr John Beddard. Note the ground flanks and the Tufnol timing gear.

Regards

Gray

[HopperParticipant @hopper]

Wasn’t there article in MEW in the past 5 years or so on making a cam grinder? By Alex Du Pre?

 

[DiogenesParticipant @diogenes]

Four parts from Issue 275 (Dec 2018) until 278 (Mar 2019), according to the index – well remembered.

[Charles LamontParticipant @charleslamont71117]

Here are some photos of my camshaft grinder:

[ZAPJACKParticipant @zapjack]

Very nice machine!

Did you have some drawings?

Regards

LeZap

[Charles LamontParticipant @charleslamont71117]

Thanks. Sorry, I am not doing drawings. Here are some design points:

The wheelhead uses a 2800rpm motor with a step-up 5mm pitch toothed belt.

The wheelhead slides along the bottom rail to get to each cam.

There is a little coolant spray nozzle mounted on the wheel guard.

The wheel guard was supposed to collect and drain the coolant. It doesn’t. It goes everywhere. The whole area has to be loosely packed with paper towel.

The camshaft is carried in the rocking cradle above the wheel.

The big disc with curved slots is a protractor for setting the relative angular positions of the cams.

The master cam is scaled up 5:1 and there is a 5:1 ratio in the radius of the camshaft and master cam from the pivot bar (the one that passes through the wheel guard).

There are two important features to preserve accurate reproduction of the master cam that are often neglected in other designs: the master cam bears on a delrin ‘shoe’ that has a radius 5 times the radius of the grinding wheel, and the height of the pivot bar can be adjusted so that the pivot bar, the top of the grinding wheel and the top of the master cam’s shoe can all be set to be in a straight line when the cam is at finished size.

The camshaft and master cam are driven at 10 rpm by a geared motor. The toothed belt drive has very little wrap round the motor pulley, but it works OK.

The master shoe moves up and down to apply cut. It sits on a wedge with a 1 in 5 slope. The wedge is moved in and out by a 40tpi micrometer screw. The wedge slope and the arm length ratio combine to give a 25:1 ratio, so one turn of the micrometer screw puts on a cut of 0.001″. 20 divisions on the knob mean that one division takes 0.0001″ off the cam diameter.

I have a tool for synchonising the camshaft with the master cam.

I had intended a worm drive from the master cam spindle to oscillate the rocking cradle slowly over the width of the grinding wheel, but that did not get made (yet).

 

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