That can lead to tear out on the underside. Once it engages the pilot hole, apply pressure to the work and drill deeper. The bit will try to align and centre itself on the pilot hole below – so let it. The drilling is easy and the technique simple… Apply very little pressure the work and gently lower the setp drill. This maxed at 12mm which is prefect for my needs here and it makes easy work of this process. I removed the work and sanded the burs from the underside before adding a step drill to the chuck. Obviously you only need to pilot drill the daps between the teeth (not the teeth themselves – even then we marked a centre point with the bradwal pin). With the drilling points marked it was a simple matter of placing a 2mm drill bit into the press and boring out a few holes pilot. Remember, it’s necessary to mark all the centre marks on the template, the ones for drilling and the ones that we add ourselves! Turning the work on the compass jig meant that each subsequent mark I made was always going to be same distance from the centre and it made lining up these points much easier. This meant that with the lightest of pressure I was able to mark a hole for drilling without fear of slipping. With careful adjustment I was able to position the point of my bradawl pin to be exactly on the one of the drilling points on the template. With everything removed from the drill press, the 2mm drill is pushed into the sprocket and then into the deck – making a simple compass jig. I carefully marked the centre of my sprocket-work, drilled a 2mm hole through the centre and drilled down a little further into the clamped wood (deck). I clamped a scrap of timber to the drill table. I placed a simple panel pin my drill chuck, turned on my angle grinder and drill and by carefully bringing the two together I was able to make a very sharp metal bradawl pin for my drill press. So I decided to centre mark with a bradwal of my own.
I guess I’m not as skilled as he is… plus the inaccuracies in the print meant I couldn’t rely on the positions of such points too much. A simple slip would easily mess things up.
The problem is using a bradawl to prone to mistake. With a template glued to a suitable piece of timber (I used MDF by plywood would be stronger and more durable), Matthias suggests using a bradawl to punch the marked drill centres on his templates ready to dill out material. In other words both the sprockets you see on this page will run on the same chain. The tooth and gap dimension are the same but the number of teeth is different.
If I’ve confused you by swapping sprockets, don’t be. More about that later… Amended sprocket template These lines dissected each tooth in two to provide a centre point to a 13mm circle which is the size of the each tooth. This meant that the diameter of each tooth had to be 13mm.īecause of this I drew some additional lines onto the template. My sprocket had teeth that were 25mm apart with gap of 12mm between. It prints to scale and also lists the critical dimensions and shows the points which need drilling out. This is one of the paper templates I printed. To begin with you’ve got look at the template the gear program produces and to try to understand what’s going on. As such I had a couple of unsuccessful builds that I certainly didn’t want to use as templates. I found my circles weren’t true so the measurements were off (whether this was my printer, the paper quality, the paper stretching with glue, etc, I’m not sure).
More critically I found that despite using his gear program correctly, my paper templates were never very accurate. Whether I used a lot or a little amount of glue, I invariably found that the template would tear apart throughout the process, leaving me with no guidelines. Now this is a great theory and I’m guessing it’s worked well for him and thousands of others – but not for me. Matthias instructs us to cut out the template, glue it to a scrap of wood, drill out some holes, trim away the excess with a bandsaw then sand to finish.
The gear generator program allows the user to type in their required measurements and from this it produces a paper template. Think of a bicycle, where the pedals meet the chain. Sprockets are similar in appearence to gears but they work in conjunction with a chain rather than another gear.
Unfortunately I needed sprockets and these are not part of the free version, but Matthias’s download version does cope with these and is very reasonably priced. You can see it online on his website See the accompanying video here. Matthias is the wood gears guru in my opinion and his program is easy and in part free. I needed to make sprockets as templates for some lost foam casting I had in mind and like a lot of people I came across Matthias Wandel’s excellent Wood Gear Generator program. Wooden Sprockets Cutting Wood Sprockets & Gears Using A Simple Jig