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  1. #1
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    Default (WIP) RH Pentz cyclone, DIY 16" BC impeller & 3Kw Teco & Vevor VFD

    This thread spun off from Clearvue install & shop layout - thoughts and feedback appreciated!

    I (& helpers) am building a Pentz 18" cyclone at the woodcraft guild of the ACT, in the metal workshop (aka "the forge", smithy, maintenance shed).

    The purpose of the project is to see if we can do it, successfully, and potentially build 4x units to service our main workshop.

    The first unit will service a 20" wadkin bandsaw and a 12" drop saw. The Bosch glide drop saw will have a round (crescent) steel sheet concentrator behind it with 2x BMH ports, one either side of the blade. The Wadkin will have 1 port in the base as standard and some sort of a pickup port behind the lower guides.

    The cyclone is 18" diameter in the main cylinder, the intake will be 225mm diameter square to round transition, which I may neck down with a metal cone if needed. The cyclone body is made from 1.0mm cold rolled sheet, as I did not want to weld Galv or anything exotic on the first unit. It is all seam welded.
    The parts were rolled on a 900mm slip roller and joints on a hand bead roller (Jenny). We machined the bead rolls ourselves.

    I have bought a 3Kw Teco 3Ph motor with a 28mm shaft & flange mount, and a Vevor 5.5Kw VFD which will accept single phase or 3 phase input.

    The plan is to make an impeller very similar to the CV 16" unit, but right handed. The back plate will be 4mm steel, the fins 3mm steel overhanging the back plate by 25.4mm. The parts will be cut out with a plasma torch(when I get time, after I have a bit of a practice). The fins will be mig welded to the backing plate. I will buy a weldable hub from our local supplier out in Fyshwick. I will buy a matching taperlock at the same place.

    The impeller will be balanced initially on a simple jig. We will turn a 28mm dummy shaft and mount the impeller using the taperlock. The shaft will then be hand spun on 4 bearings on the jig. The heavy side should come to rest on the bottom, so we can either drill weight from the backing plate on the heavy side, or Mig weight onto the backing plate on the light side. The balance will be tested by putting the dummy shaft on 2 "knife edges" as suggested by Chris Parkes. I will get the boys in the forge to mill me up an appropriate key.

    The impeller housing will be made from 16mm form ply top and bottom, with 6mm polycarbonate as the side enclosure panel(s), in a routed channel, so the impeller can be inspected. Pretty similar to the BillPentz/CV bolted MDF version. I may add a bit of strengthening alloy angle support

    The bin will be a 240 liter wheelie bin with a 2" thick wooden plug fit insert as the top. The plug insert will be supported at the top edge of the bin with something or other pragmatic... The point will be to see if the bin gets crushed, or needs further reinforcing.

    The frame will be a mobile angle iron test rig on wheels. I plan to set it up outside the main workshop (ducting thru a roll-a-door) until we have full confidence in the impeller. If we subsequently decide to make it into a production setup, it will still be outside, just in a different spot with no wheels.

    I have a spare 2.2 Kw 3Ph motor lying around with a 12" radial impeller on it. I am inclined to pull the impeller off, make a 14" backward sloped impeller and attach it with a welded hub/taper lock, then put together a custom housing,just because it would be useful to have a practice run. If the 16" impeller is successful, I plan to have a go at 17" & 18" versions.
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  3. #2
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    Quote Originally Posted by T91 View Post
    I have a spare 2.2 Kw 3Ph motor lying around with a 12" radial impeller on it. I am inclined to pull the impeller off, make a 14" backward sloped impeller and attach it with a welded hub/taper lock, then put together a custom housing,just because it would be useful to have a practice run. If the 16" impeller is successful, I plan to have a go at 17" & 18" versions.
    Depending on input constrictions a larger motor than 3HP may be needed for a 14" impeller as it may cause the motor to draw too much current. Also make sure you have a meaningful max current set up on the VFD.

  4. #3
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    Thanks for this thread T91... I'll be following it with keen interest.


    Quote Originally Posted by T91 View Post

    The bin will be a 240 liter wheelie bin with a 2" thick wooden plug fit insert as the top. The plug insert will be supported at the top edge of the bin with something or other pragmatic... The point will be to see if the bin gets crushed, or needs further reinforcing.
    I'm not clear about the possible issue of the bin being crushed... do you mean from the negative pressure in the cyclone?
    Stay sharp and stay safe!

    Neil



  5. #4
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    In a custom build I would be going to 17" at least. Having been to The Guild and discussed this previously and knowing what is required 16" was always going to be too small especially to service the lathes.
    CHRIS

  6. #5
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    Quote Originally Posted by NeilS View Post
    Thanks for this thread T91... I'll be following it with keen interest.




    I'm not clear about the possible issue of the bin being crushed... do you mean from the negative pressure in the cyclone?
    Neil, It is a problem I have seen in my own system, I am using 205 litre plastic drums and my 1800 at 70hz will partially collapse one if all gates are closed. The ideal solution might be a vent that opens in the bin or lid to supply air when the system gates are closed. It is something I have just begun to think about because I emptied the bin on mine the other day and was reminded of the problem. The other approach is a gate that mechanically opens due to the air supply being cut off when all the gates are closed, I have seen one attempt at this that was only partially successful.
    CHRIS

  7. #6
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    Quote Originally Posted by Chris Parks View Post
    Neil, It is a problem I have seen in my own system, I am using 205 litre plastic drums and my 1800 at 70hz will partially collapse one if all gates are closed.
    OK, I haven't seen that happening with the 140L wheelie bin on mine, but that is smaller in cross section and I'm only chugging along at 50Hz.

    But, the flexy hose lengths definitely convulse if all inlets get suddenly closed...
    Stay sharp and stay safe!

    Neil



  8. #7
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    Quote Originally Posted by T91 View Post
    I have bought a 3Kw Teco 3Ph motor with a 28mm shaft & flange mount, and a Vevor 5.5Kw VFD which will accept single phase or 3 phase input.
    Can you provide a model number for the VFD? I haven't seen one that will accept both single and 3 phase. (Just googled it, it looks like it will accept US 220V 3 phase input, not Aus 415V 3 phase.)
    Those were the droids I was looking for.
    https://autoblastgates.com.au

  9. #8
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    Quote Originally Posted by NCArcher View Post
    Can you provide a model number for the VFD? I haven't seen one that will accept both single and 3 phase. (Just googled it, it looks like it will accept US 220V 3 phase input,not Aus 415V 3 phase.)
    Variable Frequency Drive, VFD Drive, 5.5KW 220V Phase Converter In 1 or 3 Phase | VEVOR AU
    The specs say 220/380 +/- 15%. 220 + 15% is up to 253V, so it should be OK. If not, it was an ebay purchase, so I will ask for my money back

    I intend to use it as a driver unit for both 240v & 415v when testing both motors at various Hz while I monitor current draw with whatever impeller I happen to attach.

    The point of the VFD is to have something relatively cheap & flexible. If I burn it out, it is relatively cheap and I will know how well it performs under real world circumstances. If I burnout the old 2.2KW 415v 3ph Delta config, I dont really care, If I burn out the new 3Kw Teco, I may shed a tear, but it is unlikely to dim my enthusiasm too much.

    I will be in test & monitor mode for quite some time, as I have about 400 cranky old men [&~150 charming ladies] to convince about the benefits of decent dust extraction (modeled on the Robertson Men's shed implementation). This project is coming out of my pocket. The guild may end up going for a DIY solution like the one I am funding, or they may hire a contractor to get an off the shelf solution, or go in some other direction... My purpose is to get something relatively simple that works well on a couple of problematic machines, and does air exchange on the main workshop as a demonstration unit (I will leave the BMHs on the drop saw shroud permanently open). In the process I am hoping to get the wider membership to trust that we have the skills to get something practical up and working. That is the reason I will run the ducting out the door, and am not planning on knocking holes in walls. It is purely a developmental exercise to generate enthusiasm for dust extraction, decent ducting, custom machine hoods, and to promote awareness of the skill sets we can harness internal to the guild.

    Brendan

  10. #9
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    On the issue of the bin..

    A 240 liter bin is the right size and shape to replace our 205 liter steel bins, strapped on moving trolleys. I empty a steel bin up to 4 times a day, which are a PITA to lug 150m up the hill to dump in the horse manure compound, detach from the trolley, lift upended to empty, reattach and move back & reinstall.

    Having a swap in/swap out wheelie bin would mean much less downtime. Having wheels permanently on would be convenient. Wheelie bins are lighter (15Kg) and available in translucent so it is easier to see when they are getting full.

    If the side walls are not strong enough, I have several ideas on how they can be reinforced, or how the heavy duty lid can have a spring tensioned vacuum relief valve incorporated into it.

    Either way, I am getting older, so I want something more modular & convenient that is cheap & can be replicated easily. The 240L wheelie bin has therefore become part of the project.

    B

  11. #10
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    While we are on the subject of VFD's, Chris...
    I am keen to try out a PowTran. Which model PowTran VFD are Helensburgh running?

    What size motor would you think is best for a 17" impeller? I know Helensburgh run 7.5Hp but I am unsure of the style of fan involved, or the dimensions of the blades. If you could talk your local men's shed into getting a few photos and measurements, I'd appreciate it.

    thanks
    Brendan

  12. #11
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    Quote Originally Posted by T91 View Post

    Having a swap in/swap out wheelie bin would mean much less downtime. Having wheels permanently on would be convenient. Wheelie bins are lighter (15Kg)...
    Brendan, for what it is worth...

    At our Men's Shed they have a slide in and out drop box lined with these.

    Saxon 268L 67 x 67 x 76cm Garden Bag - Bunnings Australia

    Full bags are lifted out with the convenient handles and a fresh bag is dropped in. They are cheap enough to have a half dozen of them and the full bags can be emptied as a batch. The bags themselves are very light and the handles near the bottom make the task of upending them to empty a relatively easy task.

    Of course, the gasket on top of the drop box has to be airtight not only to ensure that the cyclone functions correctly but also to avoid sucking the bag up through the cyclone into the impeller. To quote Bill Pentz...

    "The dust chute is sealed tightly to the bottom of the cyclone with no air leaks to stir up the collected dust."

    It may not seem immediately logical, but in a properly designed cyclone the zone below where the vortex reverses at the bottom of the cone there is next to no air movement or turbulence... as it were, the calm eye of the storm.
    Stay sharp and stay safe!

    Neil



  13. #12
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    Quote Originally Posted by NeilS View Post

    At our Men's Shed they have a slide in and out drop box lined with these.

    Saxon 268L 67 x 67 x 76cm Garden Bag - Bunnings Australia

    Full bags are lifted out with the convenient handles and a fresh bag is dropped in.
    I noticed that Laguna use a metal sleeve insert that fits in the bag to hold it in place until emptied. I presume that it is slid out before the bag is lifted out.
    That would certainly add a safety margin in case an air leak develops at the seal between the cyclone and bin.... or if someone should fire up the cyclone before the bin is properly re-attached... or simply forgotten to be re-attach as I heard was the case at one Shed!
    Stay sharp and stay safe!

    Neil



  14. #13
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    Quote Originally Posted by T91 View Post
    While we are on the subject of VFD's, Chris...
    I am keen to try out a PowTran. Which model PowTran VFD are Helensburgh running?

    What size motor would you think is best for a 17" impeller? I know Helensburgh run 7.5Hp but I am unsure of the style of fan involved, or the dimensions of the blades. If you could talk your local men's shed into getting a few photos and measurements, I'd appreciate it.

    thanks
    Brendan
    Brendan, my apologies for missing this post, I am pretty sure we put a 7.5kw VFD into HMS, I know it was totally different to the lower power units in a lot of ways. As for the motor, it is 7.5hp but there is no way they will pull it apart to have a look at the fan. I would just enlarge the Max to 17" and call it job done if it was me. We are looking at a 17" cyclone but that might or might not happen and if it does not until a lot later this year. This is the one HMS has but we took all the filter and extraneous crap off and exhausted straight to atmosphere and it sucks big time.

    MWE-207CF Cyclone Unit – Major Woodworking Equipment
    CHRIS

  15. #14
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    Quote Originally Posted by NeilS View Post
    I noticed that Laguna use a metal sleeve insert that fits in the bag to hold it in place until emptied. I presume that it is slid out before the bag is lifted out.
    That would certainly add a safety margin in case an air leak develops at the seal between the cyclone and bin.... or if someone should fire up the cyclone before the bin is properly re-attached... or simply forgotten to be re-attach as I heard was the case at one Shed!
    Certainly does - works well, and if you want to fit one to any other bin beneath a cyclone then the base tube off one of those outdoor/patio gas powered heat lantern works well

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