Lozzard Posted March 9, 2017 Posted March 9, 2017 Hi all , Just after a bit advice as I am in the process of building a visco machine ,I'm using timber as I'm a carpenter and have all the tools and scrap timber lying around here at home ,I have Bosch drill press ,I can get the revolutions down to 200 rpm and up higher , this is what I intend to use as a driver with pulleys and cogs to power spindles etc , first question is " should I try working out some cog that looks like the jagged sawtooth type or make it out of a circle piece of thinner ply and work out intervals and drill dowels in ,second question is " is there any special ratio or formula for circumferences to 1 work our teeth etc to rpm ? Ive never build or worked with cogs or gearing really before cause I work with timber .How far away should. Keep the press from the hopper so as not to ignite? Safe working distance from elec etc? I've had a look through forums but I'm yet to come across it ,maybe I'm looking wrong place ,anyhow any feedback appreciated and I will post progress pics when I work out how to import them from iPad . Kind regards Lozzard
NeighborJ Posted March 9, 2017 Posted March 9, 2017 To the question about electrical distance: I believe most drill presses use motors with a start winding, this means it will have a primary and secondary motor winding. After the motor starts to spin, a current Relay switch will open to drop the e- to the start winding. This Relay is a potential point of ignition and should not be used anywhere near the fuse powder you will be using. Some press motors are permanent split phase motors and will lack the Relay contacts but they still can pose a risk of ignition from buildup of comp on the windings and overheating them. See if the press motor has an ID tag maybe with a little more info we can determine what kind it is. I believe a press can be used if the motor is changed out for one with an explosion proof housing, this is often a deal breaker because they are expensive and the brackets may need modified. The second fire hazard comes from the on off switch which can be left in the on position so the press can be remotely plugged in. To the gearing question: I'd use cogs, the peggs are reliable and easy to make. The meshed wooden gears would be difficult to make mesh properly IMO.
Lozzard Posted March 9, 2017 Author Posted March 9, 2017 Thanks mate ,I just found a good site that explains the ratios ,and will def go with dowel ,bugger getting the tapers needed the other way ,I think I might just scrap the drill press idea and go with a hand powered version ,a tad safer and less belts I'm thinking ,cheers
lloyd Posted March 9, 2017 Posted March 9, 2017 (edited) "After the motor starts to spin, a current Relay switch will open to drop the e- to the start winding. This Relay is a potential point of ignition and should not be used anywhere near the fuse powder you will be using. Some press motors are permanent split phase motors and will lack the Relay contacts but they still can pose a risk of ignition from buildup of comp on the windings and overheating them."------------------This is sound advice. I'd like to correct a minor thing, and add something. Most so-called "capacitor-start" motors use a centrifugal start switch to cut out the capacitor, and not a 'relay', per-se. I use the term 'so-called', because many such motors from appliances that start infrequently eschew the use of a capacitor (which causes a phase shift in the start winding) in favor of a winding that is actually wound out-of-phase. That sort sparks even worse than a true capacitor-start type, because the inrush current is higher during the start phase engagement. But, regardless, that relay OR centrifugal switch not only can, but ABSOLUTELY WILL make sparks. For this reason, open-frame, cap-start motors should be avoided in all pyro duties. That said, there is a plethora of small explosion-resistant (totally-enclosed, fan-cooled, or totally-enclosed non-ventilated) motors available very inexpensively off of E-Bay. Many of them are new old stock, and go for 1/10th the counter price for new. Look for "TEFC" or "TENV" motors. As far as using gears or pin-cogs on a visco machine -- I'd go with pulleys and belts... there is no 'winding ratio' on visco so critical as to cause you to have to use absolute mechanical ratios, and so long as they're designed not to slip, pulleys and belts are much easier to make AND to modify in future, if you wish to change the ratios. LLoyd Edited March 9, 2017 by lloyd 1
Twignberry Posted March 9, 2017 Posted March 9, 2017 Lozzard, I would just go with hand cranked. I don't think there's a real risk with the electric (very small qty of powder) but hand cranked is simpler. I would have gone hand cranked if I knew the numbers to shoot for. Gears work fine and as a carpenter you should be able to knock these out pretty easy (theres a template generator) https://woodgears.ca/gear/howto.html Belts work fine too The most critical part is the collection drum and collection rate. I gave some info on my thread here http://www.amateurpyro.com/forums/topic/10928-my-new-simpleish-visco-machine/?hl=%2Bvisco+%2Bmachine DO NOT make your collection drum so small. The less you bend the visco before coating, the better. I reference everything relative to the rotation of the first spindle and assume 12 threads on each spindle Have your second spindle spindle rotate opposite at about 1.2-2 rotations per rotation of the first spindle Have you collection spool geared so that it collects ~9mm thread per rotation of the first spindle. You will have to do some math, pi*diameter*RPM etc First die 2mm, second die 2.5mm hole. Ensure you have guides for the threads in the dies with a good smooth tapered leadin to ensure they wrap evenly around the thread Any other questions along the way, give me a buzz. I've been working 12 hour days for the last 3 months so response may be a bit delayed but I'll get to it eventually. 1
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