David Jenkins
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| posted on 20/2/22 at 10:54 AM |
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quote:
Originally posted by SteveWalker
It's worth doing a little more research. From what I have heard, the VFD should be reasonably closely matched to the motor. Oversizing it may
have negative consequences, but I've not looked into it myself.
I also read that in a few places while researching (I did do some!) - over-specifying the VFD is not recommended as their internal protection
circuitry, limits, etc. are usually set up for whatever rating motor they were designed to drive. I have ordered an 0.45kW VFD to drive an 0.25kW
motor (just over 1/2 HP VFD for a 1/3 HP motor).
If this VFD fails to drive that motor then they'll just get it back...
Coming back to the "toothed belt via some point of slippage" debate - It now looks likely that I will keep the current rear countershaft,
which means that there's a v-belt between the motor and the shaft carrying the first toothed pulley. That's never been a problem as
it's far away from all the oily bits. If there is a serious jam-up then the v-belt should slip... allegedly! It's more likely that the
toothed belt will strip its teeth, or similar.
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pigeondave
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| posted on 20/2/22 at 12:33 PM |
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quote:
Originally posted by rf900rush
I had a quick google for power ratings
https://www.hpcgears.com/pdf_c33/27.17-27.47.pdf
This page rates a 5mm pitch 64 tooth , 15mm wide pulley at a 1000rpm to be approx 1.7Kw
The belts generally come in 9mm,15mm and 25mm widths at 5mm tooth pitch.
I guess a 15mm or even a 25mm wide belt should work.
[Edited on 17/2/22 by rf900rush]
This is why I keep watching this forum, there's always someone who knows, or has found out some numbers to give info which is more than just a
wet finger in the air.
Brilliant post!
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David Jenkins
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| posted on 20/2/22 at 01:03 PM |
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quote:
Originally posted by pigeondave
quote:
Originally posted by rf900rush
I had a quick google for power ratings
https://www.hpcgears.com/pdf_c33/27.17-27.47.pdf
This page rates a 5mm pitch 64 tooth , 15mm wide pulley at a 1000rpm to be approx 1.7Kw
The belts generally come in 9mm,15mm and 25mm widths at 5mm tooth pitch.
I guess a 15mm or even a 25mm wide belt should work.
[Edited on 17/2/22 by rf900rush]
This is why I keep watching this forum, there's always someone who knows, or has found out some numbers to give info which is more than just a
wet finger in the air.
Brilliant post!
Yes - that url has been bookmarked for future use! 
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rf900rush
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| posted on 26/2/22 at 05:24 PM |
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Look what I found
I thought I had binned it, but searing for somthine else and found it.
If you want it, I will only ask for the cost of posting it
[Edited on 26/2/22 by rf900rush]
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David Jenkins
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| posted on 27/2/22 at 10:13 AM |
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quote:
Originally posted by rf900rush
If you want it, I will only ask for the cost of posting it
Yes please! That would make the job a lot easier, as I need the lathe to do the work to change the lathe...
Let me know how much the P&P is, and I'll PayPal it to you (if you use PP, that is). I'll PM you my address once you know.
Cheers,
David
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rf900rush
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| posted on 28/2/22 at 11:30 PM |
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Yes I have pay pal
Hopefully I will take it to work, and box it to get the correct size / weight for post costs.
A guestimate , UPS dropoff (my end drop off) is £7.50 approx.
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David Jenkins
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| posted on 6/3/22 at 03:59 PM |
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It's amazing how these projects escalate... functionality creep, it used to be called when I worked with software...
I have my VFD and 3-phase motor, and both are working very nicely on my bench. OK so far.
Then I looked at all of the hot wires that sit not very far from where fingers can reach them (these Chinese VFDs don't subscribe to good safety
management). Now I'm really experienced in dealing with live wires, but these things really aren't good and I started to get concerned -
an accidental tug on one of the cables and (a) there are live wires waving around and (b) the VFD semiconductors would probably let out the magic
smoke as it's always bad news when you disconnect the motor while the thing is running.
So I started to do some on-line research (always dodgy!) and it now looks like a Really Good Idea to mount the VFD in a steel cabinet, together with a
DIN circuit breaker and some EFI noise suppression. I planned to use external controls for the VFD, so those buttons and switches will probably go on
the cabinet door, with a cooling fan and a window so's I can see the VFD display.
And the cooling fan will need its own power supply...
And I need a new motor pulley... and they're remarkably expensive for what they are...
And I need a new countershaft pulley for the new toothed belt...
Now I just know that people will say "you don't need all that nonsense", but my personal preference is to stay alive for as long as
possible (OK so far) and to avoid electrocution. I also think it's good if the installation looks smart as well.
But, actually, despite all this, I am having fun playing with all of this stuff!
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