Boxford TCL125. (Fresh start )

[John11668]

I plan to go there Jazz, but have been working with Mach which I am moderately familiar with . Waiting the switches to give me spindle speed measurement and prove to myself I have a working machine . I have an E stop but need to reinstate interlocks and z traverse limit. Has been a steep learning curve but I would rather go a step at a time and Iinux will be one of those future steps.

[John11668]

I accept what you are saying too Paul .
I just feel I need to get it doing some plain turning first in mach . Will go to linux before I attempt any serious threading.
My target is to do a few shouldered bolts for vintage motorbikes . Linux probably has to be part of that project.

[depronman]

Just adding to Jasscnc reply. You will never get mach3 to thread correctly and reliably (been there got the tee shirt, cap and video)
The single pulse per rev is just not enough resolution to cut a thread
This was the one compelling reason that I changed to linuxcnc
Linuxcnc cut a thread on the first attempt and as done ever since The only failure I have had was when I tried to increase spindle speed beyond what the lathe could cope with in terms of accelerating the Z axis and decelerating it
I have a job that needs a M10 x 1.5 cutting on the end of an aluminium bolt. I thread at S500 in 10 passes with two spring passes fine every time.
The stability of linuxcnc over Mach3 is a very welcome bonus. Linuxcnc as never screwed up on a run of parts, I cannot say the same for mach3

now the setup of the two is a different matter all together. But a basic lathe setup can be done with the step and config wizard and is perfectly usable

Paul

[depronman]

Get it running on mach3 then but forget about the spindle speed feedback altogether until you jump to linuxcnc
It will not thread in mach3 so other than getting a spindle speed readout there is no point

Paul

[Doddy]

20mA is usually around the max rated forward current. It's a fairly conventional rule of thumb to select 10mA. That'd give a resistor of 160R, or thereabouts (selecting 10mA as the basis of the resistor calculation gives you a lot of wiggle - you can halve it and still be within the working limits, chances are you could double it and it'd still work). You get less flexibility as you chose a resistor for a larger forward current, of course.

An idealised, simplified model of an LED would presented a voltage source of V-forward (1.7, above), and 2 in series would be 3.4V. That then would mean without a series resistor you're presenting 1.6V (as you say) into a dead short - theoretically infinite current and the blue smoke escapes. Of course, the real model of the LED would have some internal series resistance, and there's the series resistance of the cabling, and the PSU. It might work. It might work for a while. It might work for not very long. But you have spares!, and if you want any resistors thrown in the post I can do that. It's an interesting experiment in any case, and you can but learn from it.

With Mach, can you confirm that with stationary spindle you get 0 RPM. Then at very low RPM you get some RPM (maybe not the right RPM, but some). The first thing you want to make sure is that the encoder input is working before getting too hooked into the inner workings. You should be able to monitor P12 input on diagnostics page and rotate the spindle by hand to find the index position - just confirm that is working with 1 PPR.

[John11668]

Would appreciate a couple of resistors suitable for the task Doddy. You still have my address I presume.
And yes spindle speed shows as zero

[Doddy]

That's the purpose of the resistor.

EDIT: I'll get a selection in the post on Monday morning.

[Kitwn]

RS Components do free delivery on all online orders which makes it economical to order only a few LEDs, resistors etc. of various values costing next to nothing for experimenting. I used to feel guilty about this and try to wait until I had a larger order, but they end up sending your order in 5 envelopes from 3 different countries anyway so don't worry about it. RS are not always the cheapest supplier but for small orders the free postage is very useful and delivery (here in Australia anyway) is quick.

If you're not sure what you need I'm sure there are several readers who could scan the online catalogue and suggest RS part numbers for you even if we don't have components we can send you directly.

[Neale]

(Deleted - retreats with egg on face due to not being able to count on fingers and get same answer twice)

[Doddy]

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