Small Circle Cutting Jig

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Boys and Girls,
 
While I’m in the process of bringing across my stuff from LJs, it’d be remiss of me to ignore this item that was first published on Mar 27, 2017 and since then, some of it’s brothers/sisters have taken up residences all around the globe … well in Aussieland, Yankeeland and somewhere in Pommyland… in fact another one left my workshop about 3 weeks ago.
 
For those that may have missed it on LJ, here it is with all the same bad grammar and spelling mistakes (maybe the obvious fixed).

Anyone interested, the 3DW,


Video of using it,


 
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This article is designed to introduce what I affectionately call my "Wall flower jig". If tends to crop up in a lot of pictures in my past projects but never gets the recognition it deserves. It is referred to as a Small Circle Cutting Jig.

All of you out there that are into toy making are aware of the dilemma of making small wheels for rolling toys. We have all seen great jigs for making wheels but most seem to be on steroids and cater for the larger type of circle sizes. To create small wheels we often fall back on the trusty (or should I call it the rusty) hole saws. Most of us can't afford diamond encrusted cutters (even those of us with lasers) so we persevere with the cheaper hole saws that burns the wood and once you finish, takes half a day to extract the wheel plug from the overheated, resin glued metal cutter.

Those that have ventured into the realms of their own circle cutter jig making, often need to ask their neighbour to help them lift their oversized circle cutting jig onto their bandsaw and hire a cab/Uber to travel from one side of it to the other. Lets face it, most circle cutters seem to have "ferris wheel size" dimensions imprinted in their designers brain which is not ideal for those tiny 2 3/4 to 6 (or so) inchers.

In turn, this jig is designed for those piddly sized circles/wheels, however, I do recommend you swap out your 1" bandsaw blade for something that can take the smaller radii.

Just to break up the suspense and give you the opportunity for a coffee break, here is a link to the video I made of using the jig.
 
While this jig has been laser cut and incorporates gears, the gears are mainly cosmetic and predominantly for bragging purposes. Without the gears, the jig is still fully functional and all cuts are straight line cuts on the table saw (or crooked line cuts with a jig saw) with a couple of slots cut for the hardware using a router (table). The jig is small and can be ported and used in a similar fashion on a disc sander to remove the bandsaw marks from the circles' perimeter.
 
The picture below shows the rack and pinion gears used to move the bottom slider,
however, they can be simply omitted and replaced by straight lines, followed by a dexterous use of either hand to achieve the same result with little or no significant effort.
 
The mitre tracks are cut out of a 3mm MDF piece to house the head of the ¼" bolt and a 6mm piece to provide support for the shaft of the bolt. Two sizes are catered for (19mm and 20mm) but they can be made as required. 
There is an adjustable travel stop to stop the jig once the blade is level with the centre spindle.
Also there is a provision for a mag-switch to secure the jig to the band saw table,
I used to say that it was an overkill and not required, but I buggered up a wheel when the jig moved while making the video, so I now have a mouthful of humble pie and an employed mag-switch.
 
The standard configuration can be used on the disc sander, however, the mag-switch is only posing as it doesn't work on the aluminium disc sander table and is only eye candy to complement the clamps… 

Unfortunately, for the other sanding profiles, it is highly recommended the jigs' components be made on a scroll saw. The central slider can be swapped out to accept the other profile sanding jigs that share a common slider.

Angles are set using a digital protractor,
 
 
SketchUp models are downloadable using this link.
 
And of course the obligatory side by side snap shot. 
The following was a prototype portrait of the jig while still in puberty. Nevertheless it wore it's gears well.

Thanks for taking the time to get to the end.
 

If your first cut is too short... Take the second cut from the longer end... LBD

Always appreciate your write ups ducky! Thank you. 

Ryan/// ~sigh~ I blew up another bowl. Moke told me "I made the inside bigger than the outside".

Interesting, well engineered.   

Ron

Just the utility of it all can work for much more than just wheels on the bus. Nice write up and plans!
Wow Ducky, that is a circle jig. Nice features. 
I remember seeing this jig and was truly impressed with the design. Thank you Alex for showing it here. 

Life’s Good, Enjoy Each New Day’s Blessings

That is another impressive jig. When I first saw the image I expected it to be much bigger - like more than twice as big.
It's only for small(ish) wheels... I have a big circle cutter for the BS,

and a router,

and of course my Fe$tool... I wouldn't be running around in circles if one foot wasn't nailed to the ground,

If your first cut is too short... Take the second cut from the longer end... LBD