I'm trying to cut some coloured pencils into small chunks or slices, less than 8mm I'm getting good square cuts when the stars align but the key is consistency. My small rotary cutting tool is fixed with a 60mm cutoff disc. The issue is throughput too. I've tried using a 32tpi blade on a hacksaw, but the friction can cause colour bleed (coloured "lead" is waxy in nature) and it just takes too long. Over 100 pieces would be a conservative estimate of number required, not too mention the variety of colours, so may need closer to 1000. Are there any sort of guides I can use to push a row of pencils squarely through the cutting disc? If I strap them together, I can obviously push them off at an angle. The answer might be to live with it and sand them as and when they are glues together in patters, but I'll take Amy suggestions at the moment.

  • Are you using a table saw? It sounds like that's what you're describing, but you just call it a "cutting tool"... By "disc" do you mean "blade"? Or are you using a grinder or something? Sep 16 '19 at 21:46
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    Also, what exactly is the cause of your inaccuracy? Pencils are generally manufactured fairly straight and the width shouldn't vary that much. Are the ferrules still on? Because I could see them messing with the stack as a whole. Maybe do a rough cut to get them off and then restack the whole thing more tightly? Sep 16 '19 at 21:49
  • It's a rotary tool as other saws are causing the colours to "bleed". I need a method to push them through bunched together so they're all square or in a row so the first and last are still square and not at an angle
    – Beerhunter
    Sep 16 '19 at 21:55
  • If you need to use an abrasive cutoff disc accurately maybe you should get a chop saw? Be careful using flammable materials on a metal-cutting tool, though... Also, I still don't understand what the source of your inaccuracy is. Are the individual shafts not uniform or is it a workholding issue? Sep 16 '19 at 23:24
  • Yes, it's a work holding issue. The tool is fixed in a vice, but the pencils are not guided and the vice doesn't have a straight edge. I didn't know if there were guides on the market for this sort of application.
    – Beerhunter
    Sep 17 '19 at 7:22

I was going to add this as another Comment but I figure it is actually an Answer since you've asked for suggestions.

If I were doing this I'd be using a Japanese-style pull saw with fairly fine teeth1, and a mitre box and with a stop clamped in place to ensure consistency. Each cut would take 1-2 strokes, literally about a second per pencil2. Triple that to account for the Law of Estimates™ and it still comes to only 50 minutes.

Factor in setup time, fiddling, occasional fumbles, moments when you stare off into space trying to remember why you're doing this :-) and I figure a full thousand would easily be tackled in one afternoon. Or 2-3 lunchtimes (it would be mindlessly repetitive and boring work, so good to spread it out).

1 A traditional dozuki would be a good choice but one of the saws from Shark would likely also work well and they'd probably be slightly cheaper. You want something in the range of 15-20 TPI.

2 Pencils are usually made from what we've come to call pencil cedar. It's not a hard wood and saws easily if you use a saw made to cut wood.

  • The Law of Estimates™ — everything takes three times longer than you think it will.
    – Graphus
    Sep 19 '19 at 7:37
  • 15-20tpi is suggested, but what about more? I will authenticate the answer once I've tried this out. Good info on the type of wood!
    – Beerhunter
    Sep 19 '19 at 9:37
  • No, more is not necessary better in this case. Smaller teeth cut slower, that's arguably the most important aspect. Now they do tend to leave a better cut surface, but the sawn face left by e.g. a 17 TPI Japanese-style saw is already super nice (almost polished, if a bit wavy or rippled). One other thing that may or may not be a factor is that the gullets (the gaps between the teeth) will be more prone to clogging the higher the tooth count. So I think 15-20 is the sweet spot for cutting efficiency and good, clean cuts.
    – Graphus
    Sep 19 '19 at 16:56
  • Well I used a razor pull saw at 24 tpi and unfortunately, it didn't cut as cleanly as the rotary tool (and I can use a standard saw quite well).
    – Beerhunter
    Sep 23 '19 at 23:22
  • You've missed the final critical clause from The Law of Estimates: "... even if you have allowed for The Law of Estimates" Sep 26 '19 at 15:52

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