Wyvern Gears

This topic has 7 replies, 4 voices, and was last updated 12 June 2017 at 23:10 by David Cambridge.

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10 November 2016 at 19:17 #265869
David Cambridge
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@davidcambridge45658
Hello All

I’m about 20% of the way into a Wyvern build. I’ve got the two gear blanks from Hemingway but I’m a bit stuck. The gear blanks have the teeth already cut, but as they are so small I’m not sure how to hold them to machine them to the dimensions shown.

They were quite expensive so I’d be grateful for some hints before I mess them up! They need to be bored inside and turned on the outside.

David
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10 November 2016 at 19:17 #8380
David Cambridge
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@davidcambridge45658
10 November 2016 at 19:33 #265877
JasonB
Moderator
@jasonb
If you have soft jaws then they can be machined to suit the gears.

If not then chuck a short bit of aluminium a bit larger in dia than the gear and bore it out to a good fit over the gear teeth, mark the bit of bar so it can go back in the chuck the same way and then remove and saw a slit lengthways.

Slip the gear into your "collet" and put them in the chuck and machine away. The slot will allow the collet to close up tight onto teh gears and being a softer metal won't damage the gear.

You may also be able to use a 5/8" collet or a 16mm ER collet with a packer at teh back end so it closes evenly.
11 November 2016 at 17:14 #266045
Chris Gunn
Participant
@chrisgunn36534
David another alternative method would be to make a 3/8" diameter mandrel to slip the gear on, tap say an M5 hole in the end, and hold it in place with a thick washer and a socket head screw, then machine the teeth away gently. Then you can turn the gear around and do the other end.

Chris Gunn
11 June 2017 at 19:52 #302122
David Cambridge
Participant
@davidcambridge45658
Hello all.

Embarrassingly , I’ve still not progressed this very far, despite the fact that it’s more than 6 months since I asked the original question.

Anyway, my question today is how are the gears actually fixed to the crankshaft. I can see there is a 1/16 notch cut into the crankshaft gear, and a 1/16 hole drilled into the camshaft gear, but it’s not clear to me how these are used to lock the rotation of the gears to the rotation of the shaft. I’m guessing it involves pins into the shafts, but I can’t see this marked on the plans.

Thanks in advance,

David
12 June 2017 at 16:32 #302235
JasonB
Moderator
@jasonb
Press fit pin into shaft, could Loctite if not happy with tightness of press fit or even use a taper pin.
12 June 2017 at 18:11 #302259
John Purdy
Participant
@johnpurdy78347
David

As Jason says a short pin is pressed into a 1/16" hole in the crankshaft to key that gear. I fixed the one on the camshaft on mine with a 1/16" roll pin. You might also read my post of 02/11/15 in the "Drawing Errors and Corrections" section of this forum (if you haven't already) as there are a number of problems with the drawings for the Wyvern.

John
12 June 2017 at 23:10 #302306
David Cambridge
Participant
@davidcambridge45658
Thanks both
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