my build

[tribbles]

That's quite impressive - I've tried that technique before (although only turning the ends of bolts), and I wasn't that successful.

Mind you, I was using an electric drill as a lathe held in one hand, and the other hand holding the grinder I was also not really after precision (just wanted a nice chamfer on the end - it wasn't very neat, but did its job).

[jonm]

tribbles
i had the drill in a stand lying on its side and clamped to the bench, because the screw was held with bearings it was running true ... there was no whip in the screw

[jonm]

been busy with work.. but found the time to to make a carridge for the gantry... made a mdf one to start...far to much flex so got out the mig pretty pleased with this one very ridgid

[jonm]

hi
went to local recycling yard today with some rubbish
and found this alu its 180mm x 90mm
this section is about 1200mm long , the other lenght is 5 meters
long,
(i see a big alu framed router) the bonus is the 6 meters of rack
that was screwed to it, how do i determine the pitch of the rack

[tribbles]

Umm - forgive me if I'm being a bit dumb - but with a ruler/micrometer?

[jonm]

hi tribbles
been looking on the net and find rack classed as mod 1
mod 2.5 etc etc all with different pitches , where do i measure from
the crown to crown of the tooth, because pitch line was talked about
that was a line about halfway up the tooth

[tribbles]

I would've thought that as long as you measure from the same point in the rack, then that's okay.

When I was looking at racks, I looked at the mod sizes, and then looked for rack that was equivalent to that size.

What's the size you have?

[jonm]

hi tribbles
pitch from crown to crown 11mm , width at top of tooth 12mm, what is mod 1, mod 2.5 refering to

[tribbles]

I'm not exactly sure what the mod setting is, but I think it's the ratio of the number of teeth to the diameter of the wheel.

I know that generally mod 1.0 means for a 60mm wheel, you get 60 teeth; for a 120mm wheel, it's 120 teeth.

So, mod 1.0 would have 3.14mm pitch (circumference = pi*dia, dia = 60, so 188.49 circumference. Divide by 60 gives pi).

If it's 11mm, then it's probably 10.995, or mod 3.5 (3.5*pi = 10.995).

[Kn8]

Hi jonm have a look at http://www.khkgears.co.jp/en/gear_te...pdf/module.pdf hopfully this will make it a but move clear.

Ivan.