3D printable Visco fuse machine

[lloyd]

A member asked me about time fuse production, which I've done "a bit of" (some 20K ft of it for a commercial company).

 

My fuse machine led two 'tracer' threads of fine cotton thread down through the powder die, in order to ensure that powder was also carried into the die. My die produced (about) a 1/16" inch-diameter core (because that's what the 'spec' was on the fuse), but the core could reasonably be as much as 1/8" in diameter.

 

Just past the powder die, ten threads of jute twine (single-ply) were wrapped around the powder core. Then, about a foot 'lower' on the machine, eight threads of the same jute were counter-wound (opposite direction) around the first wraps. At that point the 'raw' fuse is stable, but still not 'fixed'..

 

After the counter-wind, the pre-wrapped *but not-yet 'fixed'* fuse is passed through a set of compaction rollers (at HIGH pressure) to ensure that the fuse is 1) properly compacted, so the powder burns at a regular rate, and 2) so the unbound fuse is of the correct diameter for the 'finishing' operations.

 

Then the un-bound fuse (now compacted) entered a hot tar bath. While still hot,. a 'stripper die' removed excess tar, then a first 'wind' of finishing material was applied. In my case, it was fabric tape (because I was making a particular, specified, type of fuse). The material could have been paper (like common visco, but was fabric tape, because of the specifications.

 

Over that was a 'counter-wind' of the same fabric. Again, like visco, it could have been another counter-wind of a few threads to 'lock' the paper wrappings. That was followed by a quick dip in PVA-based adhesive and dye to fix the wraps and color the fuse appropriately for the contract.

 

It then passed through 48' of heated drying column (in 4 passes) to dry the PVA, and was wound on a take-up spool to be later measured and cut in 'standard' lengths for delivery to the client.

 

Lloyd

[Sleipner]

Thanks @ Lloyd I appreciate your effort describing the machine in detail.

 

About the tar, was that a particular blend you made yourself (to be just the right amount of sticky/flexible), or was it some stock standard type typically used for other purposes?

[Simoski]

I'm glad everyone is jumping in here...

@Sleipner, thanks

@Lloyd, your description of the machine you made gives me encouragement.

 

: )

 

From my side, I got side tracked by an order of black powder, and I've been printing ball mill parts.

But there is some good news I printed the funnel/die (dunnel), I was worried it would be mess up the 1.5mm hole through the middle, but I printed it very slow at 20mm per second and take a look.... the light at the end of the tunnel rings true...

 

so yes there is some progress...

is there a parallel thread?

Edited February 26, 2018 by Simoski

[Simoski]

I'm sure anyone here interested in mechanical machines willfind this channel of much interest

 

https://www.youtube.com/user/thang010146/videos

Edited February 27, 2018 by Simoski

[Sleipner]

 

is there a parallel thread?

 

Svimmer's recent thread "Homemade Visco fuse machine ! Almost done !" has some of his experiences building a visco machine.

[Simoski]

Thanks Sleipner

[Simoski]

Howsit

: )

 

here the current virtual representation of the fuse machine.

 

[lloyd]

I think you need a MUCH shorter distance between the first and second 'winds'.

 

'Just my opinion.

 

Lloyd

[Svimmer]

I think you need a MUCH shorter distance between the first and second 'winds'.

 

'Just my opinion.

 

Lloyd

Hm really ? i was planning making a new machine with more distance. so i could get the plates out easier.

[MrB]

Considering that the full size commercial machines have that 90 degree angle to add a paper layer, has a lot longer between the first platter, and the 90 degree turn, then this machine has between the platters, so i'm sort of wondering what Loyd is basing his suggestion on. Rate of travel?

 

I mean, the dude probably is the only one here who actually have owned, and operated a commercial fuse machine, so his opinion feels relevant, but i WANT him to be wrong, since i want room to add something that could add the paper layer. I like the extra strength it gives, and i think it makes it less prone to skipping ahead from stray sparks.

Edited March 10, 2018 by MrB

[lloyd]

To be sure, I'm not 'finding fault' -- just trying to be helpful.

 

Mr. B, IF you added a paper layer, then it would be fine to 'space out' the thread windings; but put the additional paper layer on soon after the first thread-wind. As it is, there's only the two thread-winding decks showing there.

 

Unless there's a LOT of tension on the raw fuse with only one winding, too much space gives a chance for the first winding to distort, making 'lumpy' fuse. It likes to unwind/expand some, even when under tension (because there's nothing but the tension preventing it... it is free to untwist some between winding decks).

 

I may have missed it, but I also did not see a 'sizing roller' to ensure the fuse (with both windings [and possible paper layer]) is of uniform diameter, before any lacquering operation. A set of compression rollers will help ensure uniform density (and thus, uniform burn rate).

 

Lloyd

[Svimmer]

To be sure, I'm not 'finding fault' -- just trying to be helpful.

 

Mr. B, IF you added a paper layer, then it would be fine to 'space out' the thread windings; but put the additional paper layer on soon after the first thread-wind. As it is, there's only the two thread-winding decks showing there.

 

Unless there's a LOT of tension on the raw fuse with only one winding, too much space gives a chance for the first winding to distort, making 'lumpy' fuse. It likes to unwind/expand some, even when under tension (because there's nothing but the tension preventing it... it is free to untwist some between winding decks).

 

I may have missed it, but I also did not see a 'sizing roller' to ensure the fuse (with both windings [and possible paper layer]) is of uniform diameter, before any lacquering operation. A set of compression rollers will help ensure uniform density (and thus, uniform burn rate).

 

Lloyd

 

What would be a good distance then ?

[Simoski]

I think you need a MUCH shorter distance between the first and second 'winds'.

 

'Just my opinion.

 

Lloyd

The current design for the superstructure is space prohibitive. I might have to learn the hard way that you're right Lloyd.

Edited March 10, 2018 by Simoski

[Simoski]

Considering that the full size commercial machines have that 90 degree angle to add a paper layer, has a lot longer between the first platter, and the 90 degree turn, then this machine has between the platters, so i'm sort of wondering what Loyd is basing his suggestion on. Rate of travel?

 

I mean, the dude probably is the only one here who actually have owned, and operated a commercial fuse machine, so his opinion feels relevant, but i WANT him to be wrong, since i want room to add something that could add the paper layer. I like the extra strength it gives, and i think it makes it less prone to skipping ahead from stray sparks.

MrB, maybe in version 2 right now I'm just aiming for basic waterproof visco. But your comment makes me feel good. I will circumvent spitting fire by not using charcoal in the composition.

[Simoski]

Brothers I'm aiming just to get my first strand of visco, in the simplest manner I can imagine, the capstan , pulleys, gearing have not yet been fully conceptualized. Anyone got a good set of 3d gear models?

 

In my mind I'm not even going to have a take up drum on version 1, just a capstan to maintain constant tension. ( clear conceptualization of simple gearing for both the capstan and the take up drum off a single motor illude me ). Fear not, not for long.

Edited March 10, 2018 by Simoski

[Baldor]

I will avoid gears if possible, use only pulleys. Modifying gear ratios is difficult, modifying a pulley ratio is as simple as printing a new pulley, or modifying an existing one with a file.

 

Also, if you want to compromise, some parts are easier made with an skill saw and a drill press, something almost everybody have access to. The plates, for example, could be made of wood or PVC. Dies on the other part are best suited for 3D printing.

[lloyd]

Baldo, on the larger time fuse machine, the gap was more-or-less dictated by the height of the spools of jute, which were about 8" high. So, on 1/4" time fuse, the 'gap' to the second wind was around 10" -- quite a lot, really.

 

The 'sizing rollers' were JUST below the second turret, and then there was a slip-clutched 'toothed pulley' just below that which kept tension on the raw fuse. I had to keep about 30-40lb of tension to resist the bulging of the yarns. That was countered up top by the combined tension of all the individual yarns, which were fed through little 'pinch disc' affairs much like thread on a sewing machine. There were 14 yarns, total, so their individual tension was low enough as not to cause the yarns to break.

 

Further down the path, just beyond the tar pot and tape winders, there was yet another tensioning roller, driven by a bit faster shaft (but also on a slip-clutch) kept the raw fuse tight until it had passed through the tar bath and first tape wind. So, it was not only tensioned between the top yarn feed and below the sizing roll, but also kept tensioned along the entire finishing path.

 

On my machine, if a bulge ever happened that prevented the fuse from feeding freely through the sizing rolls, it required a full clean-out and re-threading, losing at least an hour's time and around 40' of fuse (and of course, causing a 'break' in a run that might end up making a shorter piece than met specs). We couldn't deliver any piece shorter than 20', so during that spell, my pyro friends saw quite a bit of 'free fuse' in lengths shorter than that!! <grin>

 

Tensioning even was done between the glue-sizing pot (which 'locked' the tapes), through the heated drying column, and onto the takeup reel (which, again, was driven by a slip-clutch affair in order to keep the drying fuse tight. A reel held over 1000', so if I was careful, I didn't have to stop very often.

 

But it was ALL mechanical! If there were the slightest hiccup, it required stopping and restarting. So it was a nerve-wracking several hours of running around the machine looking for problems as it ran.

 

Lloyd

Edited March 10, 2018 by lloyd

[MrB]

To be sure, I'm not 'finding fault' -- just trying to be helpful.

Just to be clear... I was NOT suggesting that you were crapping on a design, just for the sake of crapping on it. I'm all for experience based input, and you are probably

THE most experienced one here. Getting input now, rather then with a machine that has been "done" but produces unreliable fuse, and at that point get the "Oh, i could have told you that" would make me pretty much shout "Why didn't you!". At least i appreciate the input, and would as far as possible try to understand where it's coming from, and either try to modify my design based on it, or at least know it, and expect the issue. Either way, i'd go with the "thank you for your information" approach.

 

 

Mr. B, IF you added a paper layer, then it would be fine to 'space out' the thread windings; but put the additional paper layer on soon after the first thread-wind. As it is, there's only the two thread-winding decks showing there.

Oh yes, clearly, at this point he's just working on threads, adding paper is a pet peeve of mine. I want it, and fully expect any design i go with will have to be modified to accommodate it. I'm not about to build anything from scratch on my own, i don't have the skill-set, not the equipment.

 

 

Unless there's a LOT of tension on the raw fuse with only one winding, too much space gives a chance for the first winding to distort, making 'lumpy' fuse. It likes to unwind/expand some, even when under tension (because there's nothing but the tension preventing it... it is free to untwist some between winding decks).

Oh, something like friction restriction on the thread spools. Not entirely impossible i suppose, but getting everything just right, would probably be a small nightmare.

 

 

I may have missed it, but I also did not see a 'sizing roller' to ensure the fuse (with both windings [and possible paper layer]) is of uniform diameter, before any lacquering operation. A set of compression rollers will help ensure uniform density (and thus, uniform burn rate).

Yeah, there is nothing like that in this at this point. Here comes another one of those weird questions... Since sizing rollers would be somewhat complicated to make at a high precision, and the speed of a home hobby machine like this would be rather low compared to commercial ones... would you dare a guess on if a conical die would work? Also, what does these commercial machines use for compression rollers... I suspect they are something like "peanut shaped" rollers, with the hole in the center being the expected fuse width?

 

 

The current design for the superstructure is space prohibitive. I might have to learn the hard way that you're right Lloyd.

Here is a weird suggestion... Turn the second assembly upside down? You would need a column in the middle to make the spools clear the cross-member the while thing is attached to, and the spools of thread has to be locked on to their pins in one way or another, but if the pins are replaceable anyway, just make the pin a T shape, and that should solve that part... You could have the two assembly's pretty much touching each other. You need a clever way of removing the damn thing to thread it, that still allows for it to be driven with pulleys.

 

 

MrB, maybe in version 2 right now I'm just aiming for basic waterproof visco. But your comment makes me feel good. I will circumvent spitting fire by not using charcoal in the composition.

Yeah, i fully expect to have to modify whatever i end up with anyway. Heck, i wouln't even know what source would be usable for the paper, much less where one could get it on spools cut thin enough for something like this. Don't worry about it, it's just something "I" want.

[lloyd]

"I suspect they are something like "peanut shaped" rollers, with the hole in the center being the expected fuse width?"

------------------

 

A conical die won't work, lest the fuse (at some point) be too large to fit through at the tension allowed; it would jam in the die. FWIW, the FIRST powder-entry and first capture yarns die WAS a conical die -- hardened, chromed steel, smoothed in profile in a vortex shape (like a tornado, or a swirl going down a drain).

 

I don't know what "peanut-shaped" rollers are.

 

The sizing rollers on my machine were relatively-thin pulley-like wheels, with a groove in each amounting to just a bit less than 1/3 the desired circumference of the fuse, and tapered on their outer edges so that they'd quite-nearly 'mate' in the center at exactly the compression diameter. Two were fixed in position, and one was levered into contact (HEAVY CONTACT) with the fuse by a cantilevered weight. When (almost) closed completely, they compressed the fuse to its desired final diameter prior to tarring and taping.

 

Lloyd

Edited March 11, 2018 by lloyd

[MrB]

I don't know what "peanut-shaped" rollers are.

 

The sizing rollers on my machine were relatively-thin pulley-like wheels, with a groove in each amounting to just a bit less than 1/3 the desired circumference of the fuse, and tapered on their outer edges so that they'd quite-nearly 'mate' in the center at exactly the compression diameter.

That's what they would be. Well, i imagined rounded rather then tapered on the ends, but a taper makes more sense from a machining standpoint. Thank you for your thought on the conical dies. Not that it's an accurate representation, but i'm imagining something like this for the hardened steel funnel / die?

 

Anyway, it's well past my curfew, I'll stop asking stupid stuff, and head to bed. Again, thank you for sharing.

[lloyd]

Yep... that would be the 'concept graphic' for the first powder and yarn entry die. The yarns threaded down through it (including the two 'tracer threads' that kept the powder flowing. The powder was kept at a constant level IN the funnel by a 'drip nozzle' through which the two tracers ran, so that the powder was always full in the entry funnel. The funnel was not only 'plated' on its insides, but very-nicely finished, then highly-polished. It bore a hardened mirror-finish.

 

The yarns are what actually drew the powder through the funnel -- gravity -alone- would not have brought enough through to thoroughly-compact it. At the same time, the yarns also wiped the funnel walls clean, so that only yarn remained on the outside, and only powder and tracers inside.

 

 

Lloyd

Edited March 11, 2018 by lloyd

[Simoski]

Look at you guys, not just pyromaniacs, but smart engineering types too

[lloyd]

Heh! When you own a fuse-machine, you must _become_ an engineer, if you weren't already! <smile>

 

Lloyd

[OldMarine]

Heh! When you own a fuse-machine, you must _become_ an engineer, if you weren't already! <smile>

 

Lloyd

I suspect Simoski has yet to read up on Lloyd of the Rings.

[Simoski]

I was too busy looking at the ladies in the lecture hall to really do well. I'm hoping my computer will make up for my wayward concentration.