Cutting smooth rods

I'm in the process of building the printed case version and hopefully follow in the footsteps of Eric,Pokey et al.
I'll source most of the parts myself, but will probably get a few parts from Sublime, specifically the smooth rods.
I noticed that it indicates "hardened steel". How are you guys cutting it? A quick google showed me that hardened steel
is tricky to cut - bandsaw is a no no. Next question is how difficult would drilling this be (to thread the fishing line thru)?

I would have loved to buy the acrylic kit, but to me the printed case version epitomizes the spirit of reprap. Plus it looks awesome

You can cut it with an angle grinder, or at a push a dremmel with a cf cutting disk. You might even manage it with a lot of elbow grease and a hacksaw.
If you're going to drill it, I think it will be difficult without a drill press and a decent vice.

I cut the first 5 machines worth with a good hacksaw blade and elbow grease. The ones I cut now I cut using a hand held band saw which works great but requires you to clamp them down really well. I use two sheets of wood screwed together with the rods in between which stops them from rolling and does not mark the rods.

For drilling you have to be sure to drill through in one go with even pressure (fairly hard). If you stop in the middle or go to slow you will end up work hardening the rods and breaking the bit. When I drilled the first 5 machines worth I used a had drill and broke a lot of bits. Since then I have used a drill press and managed to drill 100 holes with three bits total and I think one lasted about 80 of the holes.

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Hardened bearing shaft has caused me so much pain at work, here is my advise:

1. Hardened bearing shaft (Chrome plated steel or can be hardened 440 stainless steel if you have a large wallet) usually around 60-64 HrC (Rockwell):
I used chrome plated hardened steel bearing shaft on my Tantalus, because I had some lying around. It is great in high load applications due to is low surface roughness and hardness but as this is not a high load application. I would strongly not recommend using it. It is a bitch to cut to length as you have to use abrasive methods (angle grinder, abrasive saw etc), but the most annoying thing about it is due to its hardness it is a bitch to drill. I tried a carbide drill (also slot mill) with auto quill feed on a mill with no luck. In the end I had to spark erode the holes in, on a mates home made EDM machine. Great learning experience but a mission to do. If you find yourself in this situation, and you have no access to other shafting, I suggest find a tool maker/engineering shop with a small hole EDM drill/machine and bride them with beer to do it.

2. Centreless ground Silver Steel
This is common in NZ, has similar tolerances to drill rod on the diameter (+/-0.013mm). Usually it is used for making drills/cutters. As it is supplied in an annealed state (27HrC-35HrC apparently) you can drill/machine it easily. However it is designed to be hardened after machining, and this gives rise to the annoying fact that sublime pointed out, work hardening. If your cutter (drill in this case) is not cutting and rubbing the surface will work harden and really you have to spark erode the surface out (carbide has saved me a couple of times but risky), because it goes really hard.

This is what I am going to use for a few mates machines soon, as it is easy for me to get.

3. Drill Rod
From what I gather this is essentially the same stuff as in 2. but under different standards. I assume it is common up in north america.

If you can start the hole with a dot punch and then a centre drill as well, this will help prevent the drill from wandering when the hole starts. Drill press will help minimize drill breakages/drill life as sublime pointed out. However this stuff is probably over kill.

Thanks Guys.
Best way to learn is doing - I'll see how the angle grinder with cutoff wheel works out.

Luckily I do have a a drill press.

Angle grinder should work well. I generally use a miter saw with an abrasive blade in it for cutting the steel rod, and then use a dremel with a grinding head for beveling the rough edges.

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NewPerfection Wrote:
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> Angle grinder should work well. I generally use a
> miter saw with an abrasive blade in it for cutting
> the steel rod, and then use a dremel with a
> grinding head for beveling the rough edges.


DO NOT bevel the ends of the rods for Tantillus. The ends need to be sharp to cut the inside of the printed bushings and the Z brackets. If you bevel them you will end up with a wedge that can split the brackets and you will have drill out the printed bushings. Also any abrasive cutting method has the potential to soften or harden the drill rod because of the heat they generate.

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Sublime Wrote:
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> DO NOT bevel the ends of the rods for Tantillus.
> The ends need to be sharp to cut the inside of the
> printed bushings and the Z brackets. If you bevel
> them you will end up with a wedge that can split
> the brackets and you will have drill out the
> printed bushings. Also any abrasive cutting method
> has the potential to soften or harden the drill
> rod because of the heat they generate.

Good point on beveling the rods, I was not aware of that. The heat issue is true, although quick cuts should only generate enough heat to locally modify the rods, i.e. only at the very ends.

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> The heat issue is true, although quick
> cuts should only generate enough heat to locally
> modify the rods, i.e. only at the very ends.

Periodically dipping in coolant can prevent this. Similar to sharpening a drill/HSS lathe tool if you have a lot to take of the cutting edge.