SPP first attempt

[biggeroots]

Heres my first go at prism packing. A little way to go but will get there.

[Halfbaked]

Damn good job!

[biggeroots]

Thanks Halfbaked. I used soft stainless but need springy stuff so when it comes off the mandrel it uncoils more.

[biggeroots]

Yes rocker, I will. I only has 0.6mm to hand. Thank you.

[DAD300]

Beauty...

Now, that you know you can wind it the bug to make it has you.

That looks just like commercial Heli-pak.

A shorter mandrel will open the wraps and the tension of the wire will change the shape also.

The change of shape is just from varying the tension.

[biggeroots]

Beauty...

Now, that you know you can wind it the bug to make it has you.

That looks just like commercial Heli-pak.

A shorter mandrel will open the wraps and the tension of the wire will change the shape also.

The attachment Coils LTR r.jpg is no longer available

The change of shape is just from varying the tension.

I now have it in the bag. With the helix and spiral if you know what i mean!

[DAD300]

I think the more helix you have created now, keeps the bits from nesting.

Good job...

I also think your .6mm wire is spot on...smaller wire and the bits can crush themselves above a meter or so...

I started with .8mm wire and now have .6mm for a 2" column.

[biggeroots]

I think the more helix you have created now, keeps the bits from nesting.

Good job...

I also think your .6mm wire is spot on...smaller wire and the bits can crush themselves above a meter or so...

I started with .8mm wire and now have .6mm for a 2" column.

What diameter is your mandril?

Sorry if i hijacked the post! here's my mandrel. crap pic sorry. its about 4mm at the fat end! across corners

[DAD300]

I've made a lot of mandrels...my best is a straight screw driver blade about 4mm tapering to 2mm and a convex washer at the face.

The slot in the end is about the same as the wire dia to get you started. The coil then just pushes the bent starter out of the slot.

A flat blade will make the star shape if the tension is right and the mandrel is short.

There is a lot of variation in the mandrel that is acceptable, but keeping the coil on the mandrel is the best. It allows you to start and stop winding without loosing the coil on the mandrel.

[biggeroots]

Hi dad.Your coils are perfect! nice work, i hope to get em like that. thanks for the info.

[Soggy Bottom Boy]

Hi dad.Your coils are perfect! nice work, i hope to get em like that. thanks for the info.

Yes indeed, those are very nice!

I've made a lot of mandrels...my best is a straight screw driver blade about 4mm tapering to 2mm and a convex washer at the face.

The slot in the end is about the same as the wire dia to get you started. The coil then just pushes the bent starter out of the slot.

A flat blade will make the star shape if the tension is right and the mandrel is short. ....

DAD300, can you post up a pic of the mandrel of which you speak. ...or is that a trade secret?

[DAD300]

This pic...it has another washer floating around the outside to keep the wire off the chuck.

I have the spool of wire hung on the end of the work bench. Then wrapped around a piece of pex that helps keep the tension right without using my hand.

If the tension is too tight...the coil stays the shape of the mandrel, too loose and it comes off the mandrel, but if just right, when the wire comes off the mandrel it opens up and forms the star pattern. Although the more closed bits I made have worked very well.

[Soggy Bottom Boy]

.... I have the spool of wire hung on the end of the work bench. Then wrapped around a piece of pex that helps keep the tension right without using my hand. ....

Good idea, keep fingers away from this operation!

Wire, fingers, and an engine lathe make a mean finger-removal combination that I think warrants a strict warning to those not well versed in such things as machine tool safety. I still have all ten digits on my hands after a 40-something year career as a machinist, .....I know a few guys that cannot say the same thing, and two that got outright killed by not paying attention to, or ignoring safety protocols. Not a pretty sight.

BTW, thanks for the pic DAD300!

[DAD300]

I worked in tool design at GM a million years ago. Saw a guy get his 1970's long hair caught in a drill press once. Concussion and a VERY Permanent bald spot!

So last night I got twisted about how the straight mandrel makes a star design...took a photo that shows it.

I hope you can see how the bottom is tight to each wrap and the top is fanning off in an arc. And once it leaves the mandrel each coil springs back around the axis about 45deg for the star effect.

[crazywednesday]

Great pictures and description. Thanks for posting. Is the purpose of the notch to get it started?

[biggeroots]

Yes... very good post. Thanks

[crazywednesday]

Wire is in the mail. Can not wait to get started on the tedious task. For the interim I will use stainless scrubbies. Maybe in the next day or two I will post pics of my build. Got all my stainless piping today. Thanks for all the PM's and updating us with Pics DAD300. Your knowledge and experience is on of the things that make this a great place to congregate.

[WIski]

Dad,

What makes one side of the blade wrap tight and the other flare off loose? They look identical in the pic. Thanks for sharing.....Great info.

[DAD300]

Probably my mandrel is not perfectly symmetrical...not a designed feature. It was made by eye on a bench grinder.

[backraft]

great thread and thanks for all the pics , have tried quite a few mandrels myself the last few days and have one just like Dads and that is making the best looking spp so far,
and same from a straight screwdriver,
i tried filing some triangular shape madrels aand they just produced round coils,
cheers

[BigSwede]

You guys are killing me with these nice SPP examples. I mentioned in another thread that I want to make an SPP machine, have the whole thing in my head, but my basic attempts at getting the correct shape are not going well at all, and all the fancy auto cut stuff in the world is useless without a good form.

Dad300, what is it that allows the formed shape to slide to the right just one wire width and allow the wire to keep feeding in at the base of the mandrel? The moment mine does, the entire section loses tension and unwinds enough to lose contact with the mandrel - no more feed. If I increase tension, the wire begins to double at the base. Any suggestions? It is driving me crazy.

I'll take some pics of what I have when I get back in town.

[BigSwede]

...And here they are. Made a bit of a breakthrough when I more or less copied Dad300's mandrels. My earlier mandrels were too large.

I started in a "scientific" manner, by creating about 8 different tips from 1/4" drill rod stock.

I had a few of the washers Dad used, which are slightly convex and backed with rubber. The ones I had slipped right over the 1/4" stock and formed a nice base for the wire feed.

The blanks... I tried several tapers from 2 degrees to 6 degrees. In the end, I found a 5 degree taper works best, releases nicely, and provides adequate friction for the wind.

These blanks were then hollow cut just like a screwdriver bit, but I used a 3/16" end mill. The average tip diameter was about 3.2mm, and at the root, maybe 5mm, but it varied. They all formed decent spirals, and the smaller sizes made smaller SPP, obviously.

[BigSwede]

I was happy when I got some OK forms:

But try as I might, I absolutely could NOT get them to open, and have staggered lobes. At best, what I had were closed springs, and you may as well buy SS springs, because these wouldn't work any better.

I went bat-shit crazy all afternoon trying to get a wind that would properly open up as it left the mandrel. None of them did. I tried grooves, triangular forms, "D" bit shapes, etc etc. Super frustrated. I thought asymmetry was the key. Here was one attempt:

And you can see the whackiest effort in the tool upper left in the first picture of this post. That certainly didn't work.

They all failed. I was convinced Dad300 has Voodoo powers, or was yanking our collective chains. I don't know how he does it, but here was my "eureka" moment... I decided "Let's attack the coil AFTER it leaves the mandrel. Tweak it, pressure it." I at first tried a steel finger to do this, but that did not work, and resulted in a coiled mess. Then, I applied pressure using a ball bearing parallel to the taper, contacting the wire on the mandrel itself. This did the trick.

It took very little contact for the ball bearing to cause the lobes to skew, open, and stagger.

My daughter thought I was having a stroke when I was yelling at the setup - "You B_*^%H I kicked your ass!!" This coil is a bit large, but the fundamentals are there, just got to make a slightly smaller form, play with the ball bearing pressure a bit, and then eventually build a machine like Odin's. There's no way it'll be that fancy, but at a minimum, I'd like to have a solenoid powered cutter.

So that's it. Get a mandrel that forms OK coils, apply lateral pressure, it'll open right up.

Edit: I have a theory about Dad300's nice open coils... the wire I was using was ultra dead-soft. Zero spring. I think Dad's wire had a good bit of bounce and spring in it. In that case, it'll open with a lot less fuss that what I went through today. But I guess it's good to know it can also be done with really soft wire.

[BigSwede]

Is anyone reading this thread?

I hope you can see how the bottom is tight to each wrap and the top is fanning off in an arc. And once it leaves the mandrel each coil springs back around the axis about 45deg for the star effect.

What makes one side of the blade wrap tight and the other flare off loose? They look identical in the pic.

Probably my mandrel is not perfectly symmetrical...not a designed feature. It was made by eye on a bench grinder.

I'm still plugging away on this, spent most of yesterday still trying to get open/staggered SPP windings off the mandrel without an external influence like the ball bearing. I continued to use the dead-soft aircraft safety tie wire.

I've made upwards of 30 bits to examine how their profile affects the windings. In the end, I found nothing that worked as well as the basic screwdriver form, in varying sizes and thicknesses. To go into production, I made six from A2 tool steel which were hardened and tempered. These bits need to be hard to have decent longevity. Right out of the furnace, 1740 f, annealed 550 f.

After re-reading everything I could find, and more experiments, I had another big break through moment.

I think I can say with confidence that the fanning seen in Dad300's pics, while it might come from asymmetry, isn't what causes lobe staggering and coil separation. It's the wire. Machine-made bits with perfect symmetry produce wildly different coil forms when I change from dead-soft tie-wire to much stiffer welding wire.

The two coils above were run on the mandrel in the picture. The middle coil is soft. The lower is 316 MIG welding wire with significant spring to it. Came off the mandrel perfect, ready to cut.

Conclusion - the flat, notched bits with a convex washer form produces excellent SPP when using stainless wire with some spring to it. Copper wire will be another matter.

[BigSwede]

I apologize wholeheartedly to biggeroots and everybody for completely taking over this thread. I did not intend to... my replies kept on building and building, and in my mind this became a sort of "generic spp" kind of thread. Normal etiquette is to NOT start another thread on the same topic, but at the same time, respect the OP; it is his thread, not mine.

I cause thread drift far too often... I screwed up here. Sorry! Future SPP efforts on my part will go elsewhere.

[crazywednesday]

Thanks for the input BigSwede! Glad I bought the 316. I havent started mine yet; way too many chores around the house that need to be finished. Maybe this winter I will get to it.

[biggeroots]

I apologize wholeheartedly to biggeroots and everybody for completely taking over this thread. I did not intend to... my replies kept on building and building, and in my mind this became a sort of "generic spp" kind of thread. Normal etiquette is to NOT start another thread on the same topic, but at the same time, respect the OP; it is his thread, not mine.

I cause thread drift far too often... I screwed up here. Sorry! Future SPP efforts on my part will go elsewhere.

No problem here Swede, its all relevant, and very detailed. And there are lots of pics which is nice to see for a change!! Could do with a gallery i reckon!

[BigSwede]

Thanks for the input BigSwede! Glad I bought the 316. I havent started mine yet; way too many chores around the house that need to be finished. Maybe this winter I will get to it.

FWIW I think ANY stainless MIG welding wire will work. 316 is nice because it's super-resistant to corrosion, but it's also more expensive. Look for "Blue Demon" MIG welding wire on Amazon, they seem to be the cheapest by far, especially if you have a "Prime" membership.

The wire I used in the pic is 0.030" - too heavy, but all I had - so I ordered 0.023" / 0.6mm... I am going to cease experimenting for now until the lighter wire comes in.

No problem here Swede, its all relevant, and very detailed. And there are lots of pics which is nice to see for a change!! Could do with a gallery i reckon!

Thanks biggeroots, hope some of what I learned will help folk with SPP. It's harder than it looks.

[WIski]

Swede,

In the last picture you posted I see some steps at the base of the mandrel next to the washer. Is there any functional significance to this?

Thanks.....GREAT job and thanks for sharing.

[BigSwede]

TY, no, those grooves were a system I was using to identify mandrels, I made so many of them. On my lathe, I simply ran the tool in and cut one, two, three grooves for tools #1, #2, #3, etc; some of them I center popped with dots for ID as well. In use, the only part exposed is the blade.

Those washers are, I'd say, critical... or at least something functionally identical. What they are - just a convex washer with a rubber backing on it. A good hardware store should have them. I don't even know what they are for in the real world.

The rubber part provides friction on the mandrel. In use, you attach a washer to the bit, slide it so the wire feeds at the correct part, then secure the mandrel in your drill press chuck, lathe, whatever.