iTopSpin

Current Posts => Collecting, Modding, Turning and Spin Science => Topic started by: Jospin on December 31, 2018, 03:29:49 PM

Title: 5" delrin blanks $20 plus shipping
Post by: Jospin on December 31, 2018, 03:29:49 PM
Just ordered myself one, just in case anyone else is interested. 5 in x 5 in, close enough to make a top.
https://www.ebay.com/itm/223201152200
Title: Re: 5" delrin blanks $20 plus shipping
Post by: paxl13 on January 01, 2019, 08:27:11 AM
Dammmn why don't I have a lathe!!!!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: robtsou on January 08, 2019, 06:25:08 PM
Wow! That's pretty cheap! Thanks for the heads up!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jospin on January 08, 2019, 09:46:47 PM
Got mine, this thing is massive!  The one I got was over 5.5" long.
(https://i.imgur.com/FknrsGr.jpg)
Title: Re: 5" delrin blanks $20 plus shipping
Post by: the Earl of Whirl on January 08, 2019, 09:50:52 PM
That looks awesome.  But the top coming from that will be even more awesome!!!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: cecil on January 08, 2019, 09:52:52 PM
I love delrin but it's just to heavy. I have lot's of delrin tops and I don't use any of them. I like wood better.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Iacopo on January 09, 2019, 06:55:36 AM

I bought this material and used it for the first time a few days ago.
It is a stiff plastic, and it's easy and pleasant to turn.  It can be sanded and polished. The finish is nice.
These are the pieces I made; they are parts of a case for a top I am making in these days, which I will show you when ready.

(https://i.imgur.com/WzMIo7D.jpg)
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jeremy McCreary on January 09, 2019, 02:02:00 PM
I bought this material and used it for the first time a few days ago.
It is a stiff plastic, and it's easy and pleasant to turn.  It can be sanded and polished. The finish is nice.

The mere thought of Delrin in your hands prompted this new addition to my short list of wildest dreams: Three new tops by Maestro Simonelli, all Delrin except for their tips (and possibly their stems)...

1. An exact geometric replica of Nr. 26, one of your simplest but most studied tops -- to see how they'd compare in behavior and spin time. (This one has a sharp-edged cylindrical rotor with flat faces.)

2. An exact geometric replica of Nr. 29 for its beautiful shape and proportions. (This one has your usual round-edged flywheel with centrally recessed faces to maximize AMI per unit mass and AMI/TMI ratio.)

3. An entirely new geometric design taking advantage of Delrin's workability and finish.

This video shows Nrs. 26 and 29...

https://www.youtube.com/watch?v=_reRMxYKRr4

... but I'd be most interested in seeing what you'd come up with for (3). Of course, any of these would still take a lot of time and effort, but perhaps less than your usual metal and wood masterpieces.

Hidden agenda: A Simonelli top I can afford.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Iacopo on January 10, 2019, 06:46:28 AM
Hi Jeremy,
you have always been kind with me and I appreciate your interest for my tops,
but I have little free time for my tops and I am receiving more requests than I can manage.
I am constrained to select what commissions to accept.
Your idea to compare behaviour and spin times of Nr. 26 and 29 made with delrin could be interesting;
certainly they would spin for much less time, because delrin is much less dense than brass.
I believe that a delrin Nr. 29 would spin slightly longer than a delrin Nr. 26 because of the rounded instead of squared section of the flywheel.
I agree about your doubt to use delrin for the stem. I am not sure whether it is stiff enough to stay perfectly straight by the time.
Certainly a top made from a single piece of material would take much less time to be made, delrin also doesn't need to be varnished.
It takes some time, anyway, and at present I am too busy.  If you have the possibility to use a lathe or if you are willing to ask someone else to make them, I give you permission to duplicate them. 
 
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Iacopo on January 10, 2019, 03:53:31 PM
3. An entirely new geometric design taking advantage of Delrin's workability and finish.

The workability advantage of delrin, compared to metals, is that the material is removed much more rapidly.
So, for making large pieces, which would take many hours to be made of metal with a lathe like the mine, delrin is an interesting alternative.
In the past I used aluminum for to make the same pieces that now I made with delrin;
these pieces have a thread and are for the closing of the case of the top.  But aluminum is not slippery, while closing the case the thread tends a bit to seize, nothing serious but this is a reason that I wanted to try a different material.
I am happy about the choice because with delrin now the closing is smooth, how I feel it should be.

As for the geometry of the top, I don't think that delrin would give me more freedom than the materials I use usually.
At the countrary, delrin being a plastic, softer than metals and hardwoods, would constrain me to more massive shapes for to maintain sufficient stiffness.  Particularly, I would feel constrained to make the stems shorter and larger than I would like.
But also for the other parts of the top I wouldn't use delrin.
Cores are lighter and more beautiful when made of wood.
And, for the flywheels, metals are more suitable because of higher density, (at least, if longer spins are wanted), and more beautiful.

Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jeremy McCreary on January 10, 2019, 08:02:11 PM
I am receiving more requests than I can manage. I am constrained to select what commissions to accept.

No surprise that you're having this problem of success! The Delrin tops I mentioned were just fantasies out loud. Maybe I'll commission a Delrin top one day.

If you have the possibility to use a lathe or if you are willing to ask someone else to make them, I give you permission to duplicate them.

Thanks!

In the past I used aluminum for to make the same pieces that now I made with delrin;
these pieces have a thread and are for the closing of the case of the top.  But aluminum is not slippery, while closing the case the thread tends a bit to seize, nothing serious but this is a reason that I wanted to try a different material.
I am happy about the choice because with delrin now the closing is smooth, how I feel it should be.

Ugh, aluminum-on-aluminum threads are the worst! Not surprised that Delrin-on-Delrin worked much better.

Are you sure those Delrin parts you made aren't top rotors?

Your idea to compare behaviour and spin times of Nr. 26 and 29 made with delrin could be interesting; certainly they would spin for much less time, because delrin is much less dense than brass.

Your usual "dense metal flywheel on light wooden core" design puts its mass where it counts in a way that no structurally sound 1-piece Delrin top ever could. For a given overall shape and size, you can reach a much larger total AMI and a much larger specific AMI (AMI per unit mass) as well. The greater the latter, the lower the critical speed, and the longer the spin time. For a given total AMI, greater specific AMI also means less weight on the tip -- hence, longer spin time via smaller tip resistance.

I believe that a delrin Nr. 29 would spin slightly longer than a delrin Nr. 26 because of the rounded instead of squared section of the flywheel.

I believe that, too. As usual, the aerodynamics matter.

The workability advantage of delrin, compared to metals, is that the material is removed much more rapidly. So, for making large pieces, which would take many hours to be made of metal with a lathe like the mine, delrin is an interesting alternative.... I agree about your doubt to use delrin for the stem. I am not sure whether it is stiff enough to stay perfectly straight by the time. Certainly a top made from a single piece of material would take much less time to be made, delrin also doesn't need to be varnished.

Finding the best stem solution would take some testing. So what to test first? For Delrin's very nice feel in the hand, and for all the reasons above, I'd be inclined to test the "all one piece of Delrin besides the tip" approach first. Some plastics are pretty stiff, and some hold their shape quite well. The proprietary ABS plastic used to make LEGO parts is an amazing material (though not necessarily the best for some top designs).

As for the geometry of the top, I don't think that delrin would give me more freedom than the materials I use usually.
At the countrary, delrin being a plastic, softer than metals and hardwoods, would constrain me to more massive shapes for to maintain sufficient stiffness.  Particularly, I would feel constrained to make the stems shorter and larger than I would like.
But also for the other parts of the top I wouldn't use delrin.
Cores are lighter and more beautiful when made of wood.
And, for the flywheels, metals are more suitable because of higher density, (at least, if longer spins are wanted), and more beautiful.

Your tops are hard to beat WRT spin time, looks, and rigidity (which ultimately goes to wobble reduction). No Delrin top could compete on spin time, but Delrin could probably be made rigid enough with the right structural engineering.

As for looks, I can imagine some stunning spinnable objects in polished Delrin.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Iacopo on January 11, 2019, 03:59:16 AM
Are you sure those Delrin parts you made aren't top rotors?

They are the two lower parts of the case you can see in the design below.
The rest of the case is made of wood.

(https://i.imgur.com/S6MzxFP.jpg)
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jeremy McCreary on January 11, 2019, 04:30:02 AM
They are the two lower parts of the case you can see in the design below.
The rest of the case is made of wood.

Looks like good protection.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: butterfingers on February 07, 2019, 05:33:52 PM
Just ordered myself one, just in case anyone else is interested. 5 in x 5 in, close enough to make a top.

I just picked up several blanks from the factory which happens to be about 20 minutes from my house. The seller even gave me the nickel tour of the factory. He occasionally has other sizes of delrin available. He told me he pays $46 per foot for the 5" stock and gets it in 10' lengths! He needs 6" to make the part that he produces so anything less than 6" long that is left over becomes scrap. Smaller diameter stock results in waste pieces that are shorter lengths. He showed me a finished part (made from the 5" stock)  which is used in medical imaging equipment as a cable guide in fancy machines. It was pretty intricate and I was impressed by it. If you are interested in this guy's auctions you should save him as a seller as he told me he has the 5" stock leftovers several times a year.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jospin on February 11, 2019, 09:27:16 AM
So it begins...
Included a pic with my Giulia for perspective. Started off at 6 lbs and right now it weighs about 1.4 lb and there's still a lot of plastic that has to be trimmed off!  I'm hoping that by the time I'm done it'll be around half a pound, but that might be wishful thinking...
(https://i.imgur.com/QSozHV9.jpg)
(https://i.imgur.com/9vOJDHn.jpg)
Title: Re: 5" delrin blanks $20 plus shipping
Post by: paxl13 on February 11, 2019, 10:27:03 AM
WOW. this makes me salivate!!! This looks amazing!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: cecil on February 11, 2019, 12:48:01 PM
Looks GREAT to me. Half pound 8 oz. I like 13 oz. Make a video of it in action please, and how about a video on the lathe you are making it on?
Title: Re: 5" delrin blanks $20 plus shipping
Post by: vegabomb on February 11, 2019, 01:28:38 PM
Wow! That’s like a work of art. I can’t wait to see it finished!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: the Earl of Whirl on February 11, 2019, 11:01:11 PM
Very nice.  Looks so cool!!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jospin on February 12, 2019, 10:07:31 AM
Well finished it to a playable point.  The original plan was to make it a one way bearing top, but I kept messing up the bearing seat.  I've thought about how to fix it and eventually plan on doing that if I can.  For now I just threw together a fixed tip to slap on it and to see how it plays.  It's super fun, but extremely different.  The largest top I've played with before this was 3", so this thing feels massive!  Here's a video of me attempting to use it, might have gone better if I decided which tricks to do before I started throwing.  Ended up being 300 grams (10 1/2ish oz) with the fixed tip, that's a number I can live with!
(https://i.imgur.com/8SVhB9g.jpg)
https://youtu.be/KIrytgiHVwc
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jospin on February 12, 2019, 10:11:11 AM
Oh, just for fun I decided to see how many short circuits I could fit inside.  Sadly it was just two  ;D
Title: Re: 5" delrin blanks $20 plus shipping
Post by: paxl13 on February 12, 2019, 10:26:55 AM
WOWWW... I want one so badly... It looks amazing!!! Good job!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: ta0 on February 12, 2019, 12:12:54 PM
Fantastic!  8)

Only 300 gr for a 5" delrin top? You must have carved it really well.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jospin on February 12, 2019, 12:21:40 PM
Fantastic!  8)

Only 300 gr for a 5" delrin top? You must have carved it really well.
I was pretty nervous hollowing it out.  Took a lot of time and light passes when I got close to my target width to try to keep things from getting too thin.  The walls ended up being just shy of 4mm thick (I was shooting for 0.15"), though I did add a hair of width at the widest part (just over 1 mm).  It feels pretty solid, but we'll see how durable this thing ends up being in the long run.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: cecil on February 12, 2019, 03:24:26 PM
I think you did a FANTASTIC JOB. I like straight tips only. I want the stairway to heaven and the wire walkers. My self I would have made the wall 1/4 inch to be safe. Take that honey to the park use long line and let HER fly. JUST BEAUTIFUL.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jospin on February 12, 2019, 06:30:18 PM
I think you did a FANTASTIC JOB. I like straight tips only. I want the stairway to heaven and the wire walkers. My self I would have made the wall 1/4 inch to be safe. Take that honey to the park use long line and let HER fly. JUST BEAUTIFUL.
Thanks! 1/4" would have been way too heavy for me, I figured try making it thinner than there's not too much money down the drain as the blank was pretty cheap, but it does feel pretty solid.  We'll see what happens.
I took my camera out to take video of finishing the top up, but I set it down and completely forgot!  I'm just using the Harbor Freight Benchtop Lathe.  Most of my hollowing is done with a homemade hollowing tool made from an old screwdriver (originally was going to put a carbide insert on it, but after failing because of how hard the steel was I decided just to turn it into a hollowing tool).  The tailstock has a bit of lateral play, which is part of the reason I don't think I've been able to get a perfectly smooth top yet (though there could be more factors at play).  It's a nice and cheap little lathe, but I'm thinking about upgrading at some point...
Title: Re: 5" delrin blanks $20 plus shipping
Post by: butterfingers on February 12, 2019, 08:32:58 PM
Really nice! Is the tip also delrin? How is it attached?

Title: Re: 5" delrin blanks $20 plus shipping
Post by: Mermouy on February 12, 2019, 10:22:00 PM
Beatifut top! And it looks pretty playable!
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jospin on February 12, 2019, 10:52:59 PM
Really nice! Is the tip also delrin? How is it attached?
Yep!  Tip is also delrin.  I put a metal machine screw through the tip to reinforce it, this extends through the back of the tip and there's a nut on the inside of the top holding the tip in and in place.
Title: Re: 5" delrin blanks $20 plus shipping
Post by: Jeremy McCreary on February 13, 2019, 01:38:21 AM
Beautiful! You can't go wrong with black and white.