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  #16  
Old 11-18-2018, 05:27 PM
HO RacePro HO RacePro is offline
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I am looking for 1/32nd wheels (and/or wheels with bonded tires) that fit a 2mm axle.

I have found one set already, the JK Products T207N, but I am not entirely happy with then. For one thing they mount rubber foam tires, which are not legal in one of the classes I hope to run a direct-drive car in. For another thing, the wheels aren't nearly as wide as the tires. The outboard half of the tires are unsupported.

I'm looking for tires that are 0.720 to 0.750 inches in diameter (about 19mm). I'm not so critical about the width. If they come with tires bonded on I'm looking for foam, natural rubber and urethane. Everything except silicone.

Thanks in advance,
Ed Bianchi
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  #17  
Old 11-19-2018, 07:27 AM
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2mm is not a standard axle size, so I think that you would be left with two choices. You could use a standard wheel with a sleeve or you could have a version of a standard wheel made that has a 2mm axle hole. If you went with sleeves you might also have to ream out the standard wheels. Standard 1/32 wheels have a center ridge to locate the tire and are used with rubber, silicone and urethane tires. Foam tires are normally glued on to plain wheels. If the tires could not be glued on you would need double flange wheels.
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  #18  
Old 11-19-2018, 07:35 AM
gmcullan gmcullan is offline
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Ed, it's time to get that lathe that you've always wanted. Custom wheels with a couple of turns of the crank.
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  #19  
Old 11-19-2018, 09:29 AM
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Quote:
Originally Posted by gmcullan View Post
Ed, it's time to get that lathe that you've always wanted. Custom wheels with a couple of turns of the crank.
Hmmm... speaking as a lathe owner , that's one mighty expensive pair of wheels, both in terms of time and money (trust me, it takes more than a couple turns of the crank ).


Easiest method is likely the sleeve that RichD mentioned. You'll need some readily available K&S 3/32 brass tube and a 2mm reamer, plus a pair of whatever rims you choose with standard 3/32 inch axle holes . Cut two pieces of tubing the width of the hubs. Carefully clean/degrease both the tube and inside of the hole with alcohol or acetone, then bond the tube in the hub using cyanoacrylate or epoxy. When the glue has fully set, use the 2.00 mm reamer to enlarge the hole in the tube to 2mm size. K&S 3/32 tube has a wall thickness of .014", so the ID will be .0658" and 2mm is .0787", so you'll be taking off just over 6 thousandth of an inch (.0065"). If you want to use the grub screws with the hubs, the brass tube is thin enough that it should crush when the screw is tightened but I'd suggest grinding a flat onto the shaft where the screw will be and bonding the wheel onto the motor shaft with LocTite 262 or CA. Good luck.


cheers
Scott
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  #20  
Old 11-19-2018, 10:59 AM
HO RacePro HO RacePro is offline
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Oh Gerry, if only I could...

But it may make better sense to have custom wheels made for me by an online machine shop. Expensive, yes, but probably not a patch on what a lathe would cost me.

I have already scoped out stainless steel tubing with a 2mm ID and a 3mm OD, available on eBay. Sleeving the motor shafts is an option, but I'd prefer to avoid it.

Ed Bianchi
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  #21  
Old 11-19-2018, 02:07 PM
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Quote:
Originally Posted by RichD View Post
2mm is not a standard axle size, so I think that you would be left with two choices. You could use a standard wheel with a sleeve or you could have a version of a standard wheel made that has a 2mm axle hole. If you went with sleeves you might also have to ream out the standard wheels. Standard 1/32 wheels have a center ridge to locate the tire and are used with rubber, silicone and urethane tires. Foam tires are normally glued on to plain wheels. If the tires could not be glued on you would need double flange wheels.
NSR make wheels for 2mm axles.
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  #22  
Old 11-19-2018, 04:35 PM
gmcullan gmcullan is offline
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I've had my lathe for about 45 years now. Other than changing the drive belt and an extremely rare gibb adjustment, it has been completely trouble free. It might go months between uses, but when I need it, there is no substitute.
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  #23  
Old 11-19-2018, 10:28 PM
chrisguyw chrisguyw is offline
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Why re-invent the wheel ........as mentioned above by gascarnut, NSR makes 2.0mm bore wheels ..(NSR2005018).......or,..you can spend a whole bunch more having some custom made.

Cheers
Chris Walker
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  #24  
Old 11-20-2018, 03:05 AM
Al's slotracing Al's slotracing is offline
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It's well worth checking out suppliers of faster slot racing stuff for 3/32" to 2mm sleeves. These were pretty common about 10 years ago when the faster 1/32 and 1/24 cars were changing over from 3/32" to 2mm axles, but are much less used now that pretty much all the suppliers of quicker stuff make gears, wheel etc. with 2 mm bore.

The wheel for the faster stuff are intended for sponge tyres so tend to be smaller diameter and wider than is needed for many types solid rubber tyre.
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  #25  
Old 11-20-2018, 09:06 AM
HO RacePro HO RacePro is offline
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While I intend to build my own direct-drive chassis, I figured it was worthwhile sampling what is already commercially available -- to give me a benchmark if nothing else. So I have ordered one of the JK Products direct-drive chassis, Ready-To-Run except for a body.



For IHSR racing the front wheels need to be replaced, but I'd probably replace them anyway. I feel the role of front wheels in keeping the chassis stable is underappreciated. Otherwise I think the chassis is a good example of contemporary design.

The real lessons to be learned will center around the motor and the rear wheels/tires. Motor torque will be critical, as will tire grip. Ideally the motor will have the powerful magnets required for off-the-line performance as well as useful braking. TBD.

Ed Bianchi

PS - Gerry matches his fabrication skills with a great sense for innovative design. Leave him alone with his tools for a while, and small miracles come forth! Don't sniff about him running his lathe to 'reinvent the wheel'. If there is something to be invented he will find it!
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  #26  
Old 11-25-2018, 03:20 PM
HO RacePro HO RacePro is offline
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I received the JK Products direct drive car yesterday. I soon discovered that replacing the phony front wheels would require major surgery. Eventually I came to the conclusion it would be easier to start over from scratch.

I salvaged the motor mount and spliced it onto the back of a brass channel. Said channel was formed up from 0.031 inch thick sheet. The base of the channel is a bit over one inch wide and the sides of the channel are about 0.250 inches high. The channel itself is maybe 6 inches long.

I added a front axle tube, a Slide Guide (yes, the HO scale guide), and a pair of transverse pieces of piano wire to mount the body.

I had treated the sponge tires overnight, so they have halfway decent grip. I hope to improve on that with more treatments. Or I may go to another wheel/tire combo.

So how does the car run? As long as the pickups are working well I can turn an under-two-second lap on my 4 x 12 foot high-banked oval. Something just north of 1.900 seconds. The very best laps ever turned on this track, by an HO scale direct-drive Rattler, is a bit more than 1.600 seconds -- and that is a 'miracle' lap. Anything under 1.800 seconds is a race-winning pace.

The car handles much the same as an HO scale direct drive car. Basically you floor it through the corners and coast down the straights. It does tend to drift wide in the corners. With a little more tire grip those lap times could be pushed down a bunch.

I am playing a bit with the pickup wires to maintain best performance. I am thinking about doubling up on the pickup wires. I'm in no hurry to fall back to braid . Too stiff.

I hope to race the car next weekend at the Dauphin PA IHRS race, in the unlimited class. I'll be happy if I can score solidly mid-pack. This is an early-days development project. Hopefully some tweaks will improve its performance.

At some point I'm going to try a dual-motor direct-drive setup.

Right now, it looks like direct-drive has promise. That is what I was looking to prove at this stage.

Stay tuned,
Ed Bianchi
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  #27  
Old 11-25-2018, 11:44 PM
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Not "really" expensive or difficult.
IF...one has a small CNC screw (type) machine or access to one. A simple program, load the material, and stand back.

Mike
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  #28  
Old 11-26-2018, 02:14 PM
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I tripled the amount of pickup wire on the Slide Guide. Each side now has 135 strands of 40AWG copper wire. And that did improve the consistency of power pickup. I'm willing to call that a success.

Ed Bianchi
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  #29  
Old 12-13-2018, 01:33 PM
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Getting back to the original topic of the thread -- 1/32nd scale cars with direct drive -- I have built three of these cars to date.

The first was very loosely based on a Ready-To-Run direct drive chassis sold by JK Products. That chassis was not legal for the class I intended to race it in -- it had no useful front wheels. Fitting front wheels to it turned out to be a bear -- so I ended up doing radical surgery, replacing the front two-thirds of the chassis.

As a proof-of-concept mule it did well enough to convince me there was potential for direct-drive in 1/32nd scale. But it was too much of a kludge to bother further development. Soooooo...

I built two new chassis. One for a pre-1962 class raced by the IHRS club, and the other for their unlimited class. See below:



The chassis on the left -- for the pre-1962 class -- was built first, with carefully-designed brackets to support the motor, piano-wire frame elements, the front section from that JK Products chassis I butchered, and a pivoting mount for the front axle.

The chassis on the right -- for the unlimited class -- has a much-simplified motor mount. The motor is just epoxied onto a bracket at the rear of the chassis.

Both chassis have body mounts fabbed up from piano-wire and electrical ring-tongue terminals.

Both chassis are great examples of what I call engineer-at-assembly designs. I started out with a basic concept of how I wanted to build them, which evolved during the process of finding and fabricating parts and figuring out how to fit them together. There are always a few false starts involved, where reality shows me the failings of my conceptual design. I don't fight it. I cobble up a fix and work from there.

In the case of the unlimited chassis, my first try at a simplified motor mount turned out badly, so I scrapped it and patched together another mount. That one worked.

The pre-1962 car can nip under a 2.5 second lap on my HO-scale 4 x 12 foot high-banked oval track. That is a decent lap time for many out-of-the-box HO cars. The unlimited car can squeak under 2 seconds per lap. That's about 2 tenths of a second shy of race-winning speeds for unlimited HO cars.

It is my intention to race both cars at the IHRS race in Charleston West Virginia on Saturday. I'm hoping for good results.

Ed Bianchi
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  #30  
Old 12-14-2018, 03:40 AM
gmcullan gmcullan is offline
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Must be Ed's super secret stealth cars. Completely invisible to all eyes.
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