maybe can get one with eg. a 10:1 gearbox giving 300RPM output
"Richard Smith" wrote in message news:m1ldsc42kf.fsf@void.com...
If using flat-belts (or any other belt drive) that needs 2
countershafts, for a 3-stage speed reduction?
https://woodgears.ca/big_bandsaw/pulley.html
...
"Richard Smith" wrote in message news:m11pttet2t.fsf@void.com...
...
...
At Mitre the engineers would roughly specify the project and order
critical components before asking me to complete the design details
and handle construction. That worked out well, they knew the theory
and I knew the practice.
Earlier in the "fwiw - rod-mill project start" (concentrating then on >"metallurgical" part of rod-mill) someone mentioned continuously
variable transmission speed ratio using two disks, with one impinging on
the other at right-angles.
https://en.wikipedia.org/wiki/Friction_drive
The friction drive operates only the ground wheels, a separate pulley on the >engine shaft drives the auger and impeller on mine, with considerable >reduction to both the auger and wheel drive pulleys. The old friction disk
on my Toro slipped rather easily though the rubber rim was mostly intact. It >might be enough for a 1/2 HP motor, I'd rig a test setup before committing
it into a machine.
"Richard Smith" wrote in message news:m1wmbd29er.fsf@void.com...
Hi everyone
I have been shown how to do this with power-electronics and
"off-the-shelf" gearbox, etc. With all speed-control needed.
A friend had made a small welding positioner. Hence adapted it:
* VFD - 1ph-to-3ph
v
* 3ph induction motor
v
* worm-drive gearbox
You turn a knob setting the output Hz. Adequate speed range.
Having seen this - that it works and does everything wanted - will
simply do it this way.
Have friend's equipment on "unspecified loan' in my car to take home and
play with more.
-----------------------------------------
That is an excellent way to learn what works. The potential problems
are cost and custom machining. In that instance I'd look up and save
the components' data sheets and see how their max power ratings
compare to what was needed and what you intend to do. I've been burned
by guessing that something was good enough, my sawmill left a trail of
broken ball bearing innards until I switched to a more reputable and expensive brand for the blade guides.
I hardly ever find the same device twice as second hand and must
decide on the spot if what I found is suitable, which may depend on
its power rating. People dispose of what they can't use, typically
because they are either inadequate or broken.
I tested that contactor for pull-in voltage and contact resistance.
"Richard Smith" wrote in message news:m1v7pjhzvs.fsf@void.com...
Update these many weeks later...
...
---------------------------
Congratulations. Did you learn anything worth sharing about designing
and building low budget powered machinery?
That bit of "headroom" "saved the day".
(the device, the VFD, refuses to go above 60Hz output - likely don't
want "the heat" from people turning up at hospital with bits of motor embedded in them?)
On 30/05/2025 10:10, Richard Smith wrote:
That bit of "headroom" "saved the day".
(the device, the VFD, refuses to go above 60Hz output - likely don't
want "the heat" from people turning up at hospital with bits of motor
embedded in them?)
In my limited experience with 2 VFDs they come with a default maximum
output frequency, 50Hz IIRC with mine, which you have to change in the >configuration if you want to run faster. The first ABB VFD was changed
to 100Hz, the 2nd a Chinese one to 400Hz. RTFM.
On Fri, 30 May 2025 12:47:04 +0100, David Billington <djb@invalid.com>
wrote:
On 30/05/2025 10:10, Richard Smith wrote:
That bit of "headroom" "saved the day".
(the device, the VFD, refuses to go above 60Hz output - likely don't
want "the heat" from people turning up at hospital with bits of motor
embedded in them?)
In my limited experience with 2 VFDs they come with a default maximum >>output frequency, 50Hz IIRC with mine, which you have to change in the >>configuration if you want to run faster. The first ABB VFD was changed
to 100Hz, the 2nd a Chinese one to 400Hz. RTFM.
This is my experience too.
Joe
Thanks for writing the nice summary.
Joe Gwinn <joegwinn@comcast.net> writes:
On Fri, 30 May 2025 12:47:04 +0100, David Billington <djb@invalid.com>50% faster would generally be without unsought thrills?
wrote:
On 30/05/2025 10:10, Richard Smith wrote:This is my experience too.
That bit of "headroom" "saved the day".In my limited experience with 2 VFDs they come with a default maximum
(the device, the VFD, refuses to go above 60Hz output - likely don't
want "the heat" from people turning up at hospital with bits of motor
embedded in them?)
output frequency, 50Hz IIRC with mine, which you have to change in the
configuration if you want to run faster. The first ABB VFD was changed
to 100Hz, the 2nd a Chinese one to 400Hz. RTFM.
Joe
YOu could go a bit faster as a test with everything out of the way, then settle on what you want?
For what it's worth...
Compilation of recent events
3 videos and a photo.
I've mentioned all but most recent video already here, if recall
rightly.
http://weldsmith.co.uk/tech/minerals/250615_3vids_pics/250615_vids_pics.html "Mine and mineral recent videos and pictures"
It's our local scene here in West Cornwall - interest in geology, mining
and minerals.
All are joint endeavours
Projects have been going from strength to strength.
Most recent is separating galena - lead ore - on a shaking table.
"My" rod-mill project and the rod-mill working was a necessary link in
the chain.
I've been asked if the rod-mill is portable - ie. can it be slung in a
car and taken to where there's some minerals actions? That is how far
it's gone.
The answer is yes just about - but nowhere near as much as I'd like it
to be portable. The design where the shell rolls as it will on four
wheels, two driven - enables the cylindrical shell to be put in the
passenger footwell, where it stays put hemmed-in by the small space and balancing the car, while the frame with motor should go in the back -
maybe everything else out of the boot (truck) onto the passenger rear seats and the frame with motor in the boot so it is restrained during travel.
Else fold-down the rear passenger seats and in it all goes.
Obviously - that the mill runs on domestic "mains" easily, within a
fraction of what our "mains" can supply (always 3kW at any socket)
and could be on the end of a 10's of metres extension lead totally
helps.
The one about about the inverter VFD (Variable Frequency Drive) drawing
1ph output variable-speed driving a 3ph motor is "the biggie" I had no inkling of at the outset - as a readily achievable solution.
Best wishes,
Rich S
"David Billington" wrote in message
news:102v0bm$39cko$1@dont-email.me...
Your mill looks quite portable as is.
I added a crane like this to my pickup truck, with a home made mast
extension for taller loads such as appliances, my ~2 stone TIG/stick
welder, my milling machine and surface grinder and a friend's Atlas
lathe purchase. https://www.harborfreight.com/12-ton-capacity-pickup-truck-bed-crane-60732.html?
...-----------------------------------
How did you/they determine the amount of lead?
In first year chemistry we learned qualitative but not quantitative
analysis.
Some of the most useful chemicals for analysis are now restricted as hazardous.
"Richard Smith" wrote in message news:m1pleup761.fsf@void.com...
"Jim Wilkins" <muratlanne@gmail.com> writes:
...-----------------------------------
How did you/they determine the amount of lead?
In first year chemistry we learned qualitative but not quantitative
analysis.
Some of the most useful chemicals for analysis are now restricted as
hazardous.
Put it on a weighing scale.
57grammes
From 100g of the gelana concentrate.
It looked like lead and had a lot of density.
No assay of the metal yet.
--------------------------------
The lead may contain other similar metals such as tin, bismuth and
antimony, cupellation should have left any silver as an undissolved
bead. What was the cupel made from?
I suppose for a show-and-tell museum display the more tedious aspects
of traditional chemical analysis would be wasted, except for the few
like me who annoy the presenter with questions they can't answer.
Galena was the Crystal in early radios. It forms a Schottky barrier
diode where the metal whisker contacts it. https://en.wikipedia.org/wiki/Crystal_detector
https://people.ohio.edu/postr/bapix/CrystlRd.htm
https://www.homemade-circuits.com/point-contact-diodes-history-construction-application-circuit/
Similar Germanium contact diodes with metal spring ribbons were used
through the 1950's and later. Early US rocket launch failures
eventually were traced to the ribbon vibrating out of contact, the
noise level in the rocket is around 160 dB. Google didn’t find much on
it, I learned in person from a rocket scientist, and also about the
moon landing "computer failure" false alarm.
"Richard Smith" wrote in message news:m1a55xefiy.fsf@void.com...
Just shows the 57g lump of lead...
http://weldsmith.co.uk/tech/minerals/250622_pb_cupel/250622_pb_cupel.html "First metal extracted from gathered ore !"
-----------------------------
Congratulations, you've found the key to start civilization.
I wonder if the first to discover that had any idea of the power they
had unlocked, or just imagined shiny ornaments.
"Richard Smith" wrote in message news:m1bjqdgvuy.fsf@void.com... >Why in-general we do these things - visit the roots and thence >go forward
to knoweldgeably be at the current art.
An interest I share, as you may have noticed.
| Sysop: | Keyop |
|---|---|
| Location: | Huddersfield, West Yorkshire, UK |
| Users: | 508 |
| Nodes: | 16 (3 / 13) |
| Uptime: | 230:46:13 |
| Calls: | 9,983 |
| Calls today: | 1 |
| Files: | 13,833 |
| Messages: | 6,359,734 |
