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  1. #1
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    Default A.A. Tyson Engineer Melbourne 20" Bandsaw

    Some details of my AA Tyson restoration (a work in progress....)

    The saw is driven by a McColl Electrical Works 1hp, 3 phase, 1430 rpm motor fitted with a 3-1/2" x 2A pulley with two A61 belts driving the 10" x 2A drive pulley, resulting in a band speed of 2620 feet per minute. The motor is originally mounted on a pivoting bracket at the rear of the saw. I still need to restore the motor, and I'll probably alter it's mounting arrangement.
    IMG_1647.jpgIMG_1649.jpg

    The original drive shaft had been badly damaged, and the locking grub screws had progressively mangled the shaft. I made a replacement shaft and fitted it to the lower housing with new bearings with rubbing seals - the originals being open caged items. The band wheel shafts run in 6305 2RS ball bearings in cast iron housings. The bearing closest to the drive pulley is covered by a sheet metal disc, but on the band wheel side, there is no such cover, so I used sealed bearings throughout.
    IMG_1613.JPG

    The 20" diameter x 1-1/2" wide band wheels are cast aluminium with bonded rubber tyres. They are located on their shafts with a single locking screw. The band wheels can be adjusted between 33-1/4" and 38" centers. An 11' (or 132") band results in 36" centers. I've yet to crown and balance the wheels. Overall height to the top band wheel at its maximum position is 69".
    IMG_1642.jpgIMG_1646.jpg



    The table is 16-3/4" sq. and stands 34" high, and appears to be made of either cast steel or white (nodular) cast iron...definitely not grey cast iron like the remainder of the machine. The number 5031 (perhaps a serial number?) is stamped into the top of the table above the drive pulley. The underside of the table is stamped with a number 6 which also appears on the end of the upper band wheel shaft. The table is mounted to the cast iron frame with a simple trunion by a single bolt. I machined a stepped washer to ensure the trunion bracket remains centrally pivoted on the mounting bolt. I still need to cast a new babbit or lead throat piece in the table.
    IMG_1651.jpgIMG_1648.jpg

    The upper band guide assembly (which I believe to be original) is 2 piece cast bronze (Wright pattern), and the jaws are unhardened wrought steel (easily filed). I need to make some hardened replacement jaws as they are badly worn and scored through poor adjustment. Two round head screws on top of the casting affix the upper sheet metal blade guard. Many of the threaded holes in the casting have had threads stripped and subsequently "upsized", so there's more work to do here. I'll fill them with silver soldered bronze plugs and restore them to their former Whitworth and BA sizes.
    IMG_1639.jpgIMG_1640.jpgIMG_1641.jpgIMG_1642.jpgIMG_1654.jpg

    The guide rise and fall is achieved via a hex steel bar in a poured babbit or lead shell. The babbit is retained in the upper arm of the main frame in a simple clamshell arrangement held with two bolts, and was poured in situ. Locking of the guide rise and fall is achieved with an aluminuim hand wheel with steel threaded stud acting directly against the hex steel shaft. The maximum clearance under the guides is 9-1/4".
    IMG_1642.jpg

    The lower guide is a simple bronze casting drilled for two static guides. I'm just going to use oiled dowel for the lower guides as there is very little scope for their adjustment. Timber lower guides (of various styles) were common place in many older bandsaws.
    IMG_1645.jpg

    I have removed what I believe to be the original sheet metal guarding (in its original pale green) from the saw. It's damaged and has suffered many repairs in its former life. The metalwork is spotwelded and painted galvanised sheet, secured by brackets and in some places screwed directly to the frame of the saw. The duct in the lower guard is obviously a later modification.
    IMG_1633.jpgIMG_1635.jpgIMG_1636.jpgIMG_1637.jpgIMG_1638.jpgIMG_1634.jpg
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  3. #2
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    You have done a great job on that and thank you for getting rid of the green and for sharing. The new color looks really good.
    …..Live a Quiet Life & Work with your Hands

  4. #3
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    Nice pictures John , thanks for showing them . The upper Bronze blade guide is nice . I have the same lower bronze type. No numbers stamped on my table here that I can find . I will have to check the other saw for that. Nice looking restoration on the paint as well.

    Rob

  5. #4
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    Mar 2014
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    Beach
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    Gorgeous!!

    No other word fits. A great job of restoring that but you'll be afraid to get it dirty, what are you going to do?

    Just kidding!

    Have fun,
    Alli

  6. #5
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    Thanks Dale, Rob & Alli for your comments

    Alli - I haven't run it yet, but turned it over by hand against a piece of pine and got a bit distressed by all of the dust.....
    Not on the same scale as some of you're work!!!!

    Still plenty of work to do on this machine, and I need to make some alternative guarding - I really don't like the sheet metal, so I'll either go for timber or brass wire.

    Regards
    John

  7. #6
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    Newcastle NSW
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    Quote Originally Posted by jcge View Post
    Thanks Dale, Rob & Alli for your comments

    Alli - I haven't run it yet, but turned it over by hand against a piece of pine and got a bit distressed by all of the dust.....
    Not on the same scale as some of you're work!!!!

    Still plenty of work to do on this machine, and I need to make some alternative guarding - I really don't like the sheet metal, so I'll either go for timber or brass wire.

    Regards
    John
    John,

    I love your work, but it sounds like the best is yet to come (crowning the wheel, a bit of playing with babbit material,adding some plugs, and building a new guard), looking forward to seeing some detail on how you tackle these tasks, if you have the time.

    Cheers,

    Camo

  8. #7
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    Quote Originally Posted by camoz View Post
    .....looking forward to seeing some detail on how you tackle these tasks, if you have the time.

    Cheers,

    Camo
    Only took me 730+ days to get this far Camo....don't hold your breath !!!

  9. #8
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    Dec 2010
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    Beautiful Job John !
    You may have taken your time but the careful attention to detail and effort shows.
    Looking forward to seeing it up and running, thanks for showing !

    Melbourne Matty.

  10. #9
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    Thanks for your encouragement Matty - I'll be pretty happy when its up and running.

    Regards
    John

  11. #10
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    I've cast a new throat piece from lead/tin (scraps of solder, flashing and wheel weights) using a piece of flat steel and a tapered block of pine to provide the slot and tilt relief respectively. The steel was wedged in with the shaft of a pop rivet. I was expecting fireworks from the pine, but having positioned the table upside down on a block of steel, combined with the mass of the iron table itself, the pour cooled quickly enough that I didn't even notice any smoke from the pine. I had to break up the sacrificial pine bevel due to a bit of over pour that left it captive in the new throat plate.

    IMG_1674.jpgIMG_1673.jpgIMG_1675.jpgIMG_1676.jpgIMG_1678.jpg

    Some foreign material on the supporting steel plate, or possibly sawdust from the pine block has outgassed resulting in a little porosity in the table top surface, but not enough to warrant a re-pour. I might fill and improve the resultant surface defects with a soldering iron at a later date. It's very easy to scrape the white metal level with the iron table top. I'll clean up the slot with a file when I'm aligning blade path on the saw.

    I followed the attached tutorial with modified dimensions for my saw's throat plate relief. Shouldn't have to say it, but WARNING pouring molten metal is DANGEROUS. If you don't understand and accept the risks, don't attempt to do it.

    repouringbabbittthroats.pdf

    An important point from the tutorial....ensure the steel and timber are weighted down to prevent them floating in the molten metal.

    Regards,
    John

  12. #11
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    Good job, I'm impressed by your efforts. I had actually been wondering how I was going to pour a new one for my saw, which I didn't end up getting. Will have to save this away in the memory banks.
    …..Live a Quiet Life & Work with your Hands

  13. #12
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    Beauty John ,thanks, I was looking for that info a week ago with no luck . I was just thinking of pouring it from the top , I never even thought of the table tilt and how the throat piece needs to accommodate that . I have been fluffing around for years fitting timber ones.

    Rob

  14. #13
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    Thanks for your comments Dale & Rob

    Rob - I was only going to give the hot pour one attempt - if it had gone poorly, I would have gone straight for a timber insert. Here's a couple of other things to consider.

    I used a wooden chamfer block, but considered going with aluminium screwed to the steel bar. I could have preheated this piece to get a better pour. However an over-pour would have left me with the aluminium and steel strip stuck in the white metal. I guess using a larger block with a more refined shape where it adjoins the edge would alleviate this. If you take this route, don't forget to screw the pieces together with countersunk screws with the tops filed flush to remove the slotted head as the white metal would fill this void making removal unachievable.

    Second is choice of white metal, and it's coefficient of expansion. I used a bastard mix of lead and solder (what ever was laying about), both of which contract on cooling, and result in a solid piece that can be removed without too much problem. In this regard 60/40 tin lead (eutectic) solder would exhibit about half the shrinkage of pure lead (and also pour at about half the temperature). However, there are other low temperature alloys (search for fusible alloys or Wood's metal) that contain bismuth which expand upon freezing, and exhibit further expansion in the following hours and days. These would result in tight fitting pieces. Depending on the alloy selection, the degree of expansion can be controlled. Some of them also melt a less than 100°C.

    Third is the fill rate (speed of pouring the metal). The hot metal is coming into contact with a large mass of cold iron, and a slow pour will result in a poor casting. Controlling this is hit and miss...good luck !!!! You can see the tide lines in the picture below, but they're only shallow, hence my earlier comments about fixing them with a soldering iron (old school block of copper on a stick) and a little extra solder. I didn't preheat the table prior to the pour as I'd already painted it...

    IMG_1677.jpg

    John

  15. #14
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    I made a simple jig to mount the band wheels for crowning on the disc sander, and used the tilt of the table to provide the crown angle (not strictly a crown radius, but a V profile instead).

    Jig mounted with G clamps to the sander's table
    IMG_1687.JPG

    With wheel mounted
    IMG_1688.JPG

    The tyres had plenty of rubber in good condition so new tyres were not required. The table was tilted downwards to ensure that the cutting force acted from the centre of the tyre towards the rim to prevent any peeling action that would lift the edge of the tyre and break its bond to the wheel.

    The 60 grit disc made light work of the bonded rubber tyres. The hub of the wheel is not centered in the rim, and so simply turning the wheel over to grind the second side would not result in a crown centered across the width of the rim. The jig had to be reset on the table to get the peak of the tyre in the middle of the rim. A few passes and the tyres were crowned.

    First side complete and shows misalignment and scoring of the band prior to crowning
    IMG_1689.JPG

    Second side complete with the crown centered on the rim.
    [IMG_1690.JPG

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