Resaons for or against an Electronic Lead Screw

Hi everyone,

This subject has created an interesting flurry of postings. There seem to
be three common threads.

1. Why would you want it when for only a few dollars more (or the same
amount) you can have full CNC.

2. Don't bother; buy this product and hook up a PC to make it work then
remove the PC again.

3. This would be so useful if it were only $150 which is so much cheaper
than CNC.

None of those points address my needs in wanting one though. I see fairly
frequently postings on the South Bend Lathe group asking if someone has a
particular gear for either the gearbox (it's been damaged) or as a change
gear (it's gone missing). Then there are the lathes that don't have change
gears and move the Z axis with a permanent Leadscrew and no half nut. Or,
in the case of the South Bend, it's totally wrong to use the half nut for
feeding the carriage when the system has a slotted leadscrew, drive gears
and a clutch. Using the half nut wears out the leadscrew and the nut which
affects threading.

What I'm trying to say is the need for an Electronic Lead Screw product
isn't so much as to do automation, but to replace or reproduce a set of
change gears that drive the screw. And I'd like it to fit into a small 3x5
box not including the power supply.

Point #1 ignores size specifications a criteria for the end product. It's
like someone asking for a 7x12 manual lathe that fits on a small desktop and
being told the only solution is a 3 phase powered HAAS CNC milling station.
Price has some bearing here too obviously.

Point #1 also doesn't address a second issue because featuritus is already
changing the definition of the original idea. A rotary switch for the
spindle divisor and a second rotary switch for the leadscrew divisor are all
that are really needed to make the unit function when built with discrete
logic or an FPGA. Yes it would be nice to have a DRO but it's not the point
of the product. For the simple version some sort of thread indicator
running on the leadscrew is still required.

Point #2 is similar to saying that we have gear molds which are kept in the
front office. When you need a 32 tooth wheel, get the mold, cast the gear
and then when your need a different once melt this one down as raw material
for the 35 tooth wheel. Moving a PC back and forth to set up parameters for
a dedicated black box just isn't workable for me. Most of the time I can't
even find my desk much less a place to actually put down a PC.

Point #3 and that the assorted CNC costs the same, fall into the category of
the customer telling the engineer how much it should cost without having any
idea if it's even possible to make it for that price. Software engineers
get the same sort of thing tossed in their direction all the time. They
present a quote for the time it should take to do something and then go into
negotiations to lower the number of hours quoted. My favourite comeback to
that one is "It doesn't matter how many women you put on the job or how hard
you work them, it still takes 9 months for one women to make one baby".


At this point in time if we tried to do the original CMOS version of the
electronic gear with two rotary switches we'd probably find the cost quite
high unless a large number were made. The switches could run $30 or more.
And truthfully I'd rather have thumbwheels that show what number I've
dialled in; even more expensive. But the logic could be reduced into one
FPGA which would also reduce the size to fit into the size specification.

How much would it cost? No idea without more research. I'll post on the
E-Leadscrew list when I have more info.

John Dammeyer




Wireless CAN with the CANRF module now available.
http://www.autoartisans.com/products
Automation Artisans Inc.
Ph. 1 250 544 4950