I am currently making a chainbarlift and it seems like I have to drill a circular hole in a sprocket. I have tried multiple ways to drill a hole but it seems like it is really hard to drill a circular hole. Can anyone tell me how to drill a hole in a chainbarlift?
Just use a free spinning insert - no need to drill.
Is it possible to insert a free spinning piece in a sprocket?
Sprockets don’t use inserts, but we were able to work around that and make the other end of the axle free spin. We drilled holes in wheels for NbN and it will kind of home itself as long as you use a bit the perfect size of say a bearing flat hole.
If the sprocket has screw holes in it, can you use a piece of Vex C-Channel or Vex plate to act as a drill guide for the center hole (by first screwing such a drill guide onto the sprocket)? If the sprocket’s center hub is making it hard to align a drill, can you first snip or Dremel it out of the way?
I have to admit, I’ve never tried putting a free spinning insert into a sprocket. I’m kind of surprised that it won’t fit!
No need to drill any holes; just follow this video by Tabor a while ago.
So to answer the OP’s question, the problem is drilling out a square hole to make it round, and about the only good way to do this would be to chuck the sprocket into a lathe, and use a drill in the tailstock which has been ground with a zero-rake angle for plastics. Access to a machine shop is handy, but this could be done on a wood lathe, too.
The HS sprockets have normal axle holes. There has been a change in production to make them have HS axle holes and to come with inserts (similar to HS gears). Until current supplies are out they are selling the old sprockets.
Are all the sprockets now available with the HS (high strength) axle hole? I was under the impression that Vex has started with the smaller sprockets but has yet to make the larger sprockets available with the HS axle hole.
I thought they made all of them with new hole. The only question is which they have started actually selling as they had a different amount of stock for each size.
Could of course be wrong. @DRow mind giving an update on this?
Would just like to chime in here, although you can use the green round inserts into the HS gear I have found it more stable to use the metal square insert in the HS gear and drill a hole into the sprocket. When using the green inserts the gear would occasionally misalign or shift diagonally, changing inserts and drilling the holes fixed the issue. As to making a straight hole @kmmohn had it right, a lathe is the best, but a simple hand drill and steady hands work just fine.
On gears, I found last season (with a high-strain lift) that square inserts and a free-spinning axle was much more reliable than a fixed axle with a free-spinning gear (with a circular insert). The circular inserts tended to allow the gears more wiggle room and skipped more often.
The exception was when I got sick of axles bending on our first bot and used standoffs on either side of the gear with a circular insert and had the gear on a standoff coupler that went between the standoffs on either side. That was very sturdy and fixed the issue. To be clear, from left to right: standoff mounted to inside of metal tower, standoff coupler with gear spinning freely on it, standoff mounted to inside of metal tower.
What we do is we have a free spinning axel with free spinning gear, the bearing block (flat?) Holds the gear where it would normally, and if the circular too much friction, then the shaft moves, but if its got less then only the gear moves
This also allows to more easily change gearings down the road
Hi…