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  1. #1
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    Feb 2006
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    Perth
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    Default Bell mouth hood offer - expressions of interest

    I am about to start another production run of PVC bell mouth hoods for the men's shed.

    In another post I said I was considering making some for Perth members on a pick up only basis (cost to still be determined) and was looking for expressions of interest.
    So far no one has asked for any so am widening the offer Australia wide to the first 5 Australian members that PM me and tell me how many of each of 4" and 6" sizes they want.

    Please note that this post is to determine expressions of interest only - I just want to gauge interest,
    Costs and numbers available will be determined once I have the requests.

    Please note, do not post your requests in this thread - send me a PM including your email address so further discussion can take place by email.

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  3. #2
    Join Date
    Mar 2012
    Location
    Melbourne
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    17

    Default

    Quote Originally Posted by BobL View Post
    I am about to start another production run of PVC bell mouth hoods for the men's shed.

    In another post I said I was considering making some for Perth members on a pick up only basis (cost to still be determined) and was looking for expressions of interest.
    So far no one has asked for any so am widening the offer Australia wide to the first 5 Australian members that PM me and tell me how many of each of 4" and 6" sizes they want.

    Please note that this post is to determine expressions of interest only - I just want to gauge interest,
    Costs and numbers available will be determined once I have the requests.

    Please note, do not post your requests in this thread - send me a PM including your email address so further discussion can take place by email.
    Interested, thanks Bob, but depends on cost and postage of course. Do you have a picture?

    Sent from my Nexus 5 using Tapatalk

  4. #3
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    Feb 2006
    Location
    Perth
    Posts
    27,757

    Default

    Quote Originally Posted by loudav View Post
    Interested, thanks Bob, but depends on cost and postage of course. Do you have a picture?
    BMHs are discussed extensively in this thread Improving machine cabinet dust ports
    The 4 and 6" ones I am making are shown from Post #68 onwards in this thread - you can of course use this info to make your own.

    As I said above the cost including postage will be worked out once I know the numbers involved.
    All I am looking for at this stage is 5 persons who want to avail themselves of this exercise.
    I realise it's a bit chicken and egg at the moment but that's the only way I am prepared to do it.

    I will only take expressions of interest by PM that includes an email address and all details will be discussed outside the forum.
    By registering your interest there is no obligation to purchase all or any of your initial expression.
    I just don't want to be making and holding several dozen of these with no one to purchase them.

  5. #4
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    Feb 2006
    Location
    Perth
    Posts
    27,757

    Default

    Call that a bell mouth hood - THIS is a Bell Mouth Hood



    Link provided by Ben Hoskin

  6. #5
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    Feb 2006
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    Perth
    Posts
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    Default

    I have 5 expressions of interest but feel free to send through more and I will put you on a reserve list.

  7. #6
    Join Date
    Feb 2006
    Location
    Perth
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    Default

    Got started on the BMH production run last night and got this far by lunchtime today.
    Most of the 6" ones are done and about half the 4" ones are complete.

    IMG_1977.jpg

    It's more work than it seems but it makes a difference time wise when you get into production mode.
    The most gain in time is the BMH former retains some heat between the forming each hood so it does not take as long to heat up the former as starting from scratch.

    I'm using an IR sensor to monitor the temperature of the PVC heating which is really helpful.
    As soon as the PVC reaches ~105º I start cranking the tail stock of the lathe.
    There's enough tailstock travel to complete the 4" BMHs in one pass but the 6" hoods require a repositioning of the tailstock to get enough travel.

  8. #7
    Join Date
    Nov 2013
    Location
    Caboolture QLD AU
    Posts
    781

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    A big thank you of appreciation to Bob for all the effort and time he has put into making these BM Hoods, really nice work and thanks again Bob.

  9. #8
    Join Date
    Feb 2006
    Location
    Lindfield N.S.W.
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    62
    Posts
    5,643

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    Cheers

    Jeremy
    If it were done when 'tis done, then 'twere well it were done quickly

  10. #9
    Join Date
    May 2011
    Location
    Murray Bridge SA
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    3,339

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    Quote Originally Posted by MandJ View Post
    A big thank you of appreciation to Bob for all the effort and time he has put into making these BM Hoods, really nice work and thanks again Bob.
    The thanks and appreciation, should also be for ALL the technical knowledge and details that Bob puts up here for all to use.
    The amount of technical info here is mind blowing. Thanks again Bob.
    Kryn
    To grow old is mandatory, growing up is optional.

  11. #10
    Join Date
    Feb 2006
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    Perth
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    Bell Mouth Hood Guards

    One of the draw backs of using naked BMHs on machinery like sanders and lathes is the likelihood of losing tools, sandpaper, small work pieces and small furry animals up the BMH.

    To prevent this happening I have made and used guards like these.

    IMG_2089.jpg
    The belt sander guard was just a piece of 40 mm x 3mm wire galv mesh - it works fine although the mesh size may be a touch large for very small work pieces.
    I had another similar guard that I used on the 100 mm BMH on this sander and it was interesting to see that over a year the grit from the belt had abraded away the galv which is why I decided to go for SS for the new guards.

    latheold.jpg
    This is the old guard on my lathe. Its made of 25 mm square 2.5 mm SS and just bent and jammed into that opening.
    The lathe is a particular nuisance because curlies get trapped and the guard has to be regularly removed and cleaned.
    Extracting the mesh guard out of the opening was tricky so I wanted something easier to remove and replace.

    Although its still better than a naked piece of ducting the mesh guard also robs a lot of flow - up to 20%, which almost defeats the purpose of having a BMH.
    This especially significant for the lathe where the guard sits at the narrower back of the BMH mouth

    What I really wanted to have a was a guard that could be easily removed for optimum dust collection, for example when roughing down and shaping a large workpiece, and if necessary easily added back for sanding.

    I was going to go for the simple hook over the lip of the BMH method as shown on the Sander above but I decided to go for something a bit nicer.

    The new guard is just a 225 x 225 mm piece of 25 x 3 mm 316 SS.
    It sits on the front of the BMH using a wire loop hanger passing across the back of the BMH as shown below.
    Because the gaud sits on the wider front opening of the BMH is has less of an impact on the air flow,

    BSandernew.jpg


    lathenew.jpg


    The hanger is just a length of SS wire looped across the back of the BMH.
    The guard can easily be removed for unrestrained dust collection and quickly popped back on when needed.
    hanger.jpg

    Unfortunately the SS mesh only comes in 1.2 x 2.4 m panels.
    I have purchased a whole sheet but after making guards for myself and the mens shed there will plenty left over for interested persons who wish to purchase pieces for their hoods.

    I am also still making BMHs so PM me if you are interested in purchasing either BMHs, guards or both.

    NB the guards are only needed for naked BMHs as used on lathes and sanders. If the hoods are being used in DCs, or on cabinets or under BS then a guard is not needed.

  12. #11
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    Oct 2013
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    Perth, Australia
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    1,813

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    These are well worth the money guys, got a couple myself and will be getting more in the future.

  13. #12
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    May 2014
    Location
    Canberra
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    237

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    A cake cooling rack could maybe also do the trick? They can be purchased with the square design.

  14. #13
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    Perth
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    Quote Originally Posted by lovetoride View Post
    A cake cooling rack could maybe also do the trick? They can be purchased with the square design.
    Just looked at some of those after watching SWMBO doing a bit of baking.
    There are a couple of issues, the main one is they seem to have tightish mesh spacing which impacts on the flow.

    For example this chrome plated one is only $5 from kitchen warehouse
    It's a good size @ 200 x 250 mm, unfortunately with a 10 mm spacing this works out to have a <30% flow loss.
    cakerack.jpg
    SWMBO has this 250 mm round rack that has 2mm wires 18 mm apart that would look really tidy.
    cakerack2.jpg
    With the wires running in only one direction this is really good for flow (11% loss) although that increases the chances of the goodies getting though the guard.

    I reckon the mesh spacing should be somewhere between 25 and 30 mm with as thin a wire as possible

    cakerack1.jpg
    This one looks like it could be a good compromise but it is surprisingly restrictive.

    I will keep looking.

  15. #14
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    May 2014
    Location
    Canberra
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    237

    Default

    I went looking last night in my kitchen. I had one that was probably 2cm squares and about 30x30cm but I think my daughter took it to stock her kitchen... Convection microwaves have the circular metal ones with proabably 2mm wires but alas I gave mine away with the old microwave.

  16. #15
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    Feb 2006
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    Perth
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    Quote Originally Posted by lovetoride View Post
    I went looking last night in my kitchen. I had one that was probably 2cm squares and about 30x30cm but I think my daughter took it to stock her kitchen... .
    Sounds familiar.

    Some convention oven racks might also be OK.

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