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Author Topic: 5" delrin blanks $20 plus shipping  (Read 1783 times)

Jospin

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5" delrin blanks $20 plus shipping
« 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
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paxl13

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Re: 5" delrin blanks $20 plus shipping
« Reply #1 on: January 01, 2019, 08:27:11 AM »

Dammmn why don't I have a lathe!!!!
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robtsou

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Re: 5" delrin blanks $20 plus shipping
« Reply #2 on: January 08, 2019, 06:25:08 PM »

Wow! That's pretty cheap! Thanks for the heads up!
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Jospin

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Re: 5" delrin blanks $20 plus shipping
« Reply #3 on: January 08, 2019, 09:46:47 PM »

Got mine, this thing is massive!  The one I got was over 5.5" long.
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the Earl of Whirl

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Re: 5" delrin blanks $20 plus shipping
« Reply #4 on: January 08, 2019, 09:50:52 PM »

That looks awesome.  But the top coming from that will be even more awesome!!!
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cecil

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Re: 5" delrin blanks $20 plus shipping
« Reply #5 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.
« Last Edit: January 09, 2019, 12:19:35 AM by cecil »
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Iacopo

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Re: 5" delrin blanks $20 plus shipping
« Reply #6 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.

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Jeremy McCreary

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Re: 5" delrin blanks $20 plus shipping
« Reply #7 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.
« Last Edit: January 09, 2019, 02:24:14 PM by Jeremy McCreary »
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Iacopo

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Re: 5" delrin blanks $20 plus shipping
« Reply #8 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. 
 
« Last Edit: January 10, 2019, 02:49:47 PM by Iacopo »
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Iacopo

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Re: 5" delrin blanks $20 plus shipping
« Reply #9 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.

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Jeremy McCreary

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Re: 5" delrin blanks $20 plus shipping
« Reply #10 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.
« Last Edit: January 10, 2019, 11:49:00 PM by Jeremy McCreary »
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Iacopo

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Re: 5" delrin blanks $20 plus shipping
« Reply #11 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.


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Jeremy McCreary

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Re: 5" delrin blanks $20 plus shipping
« Reply #12 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.
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butterfingers

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Re: 5" delrin blanks $20 plus shipping
« Reply #13 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.
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Jospin

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Re: 5" delrin blanks $20 plus shipping
« Reply #14 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...

« Last Edit: February 11, 2019, 12:45:20 PM by Jospin »
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