V-Wheels machined from plastics
 

Copied from elsewhere:

. . . . . . I am using Ertalyte wheels. They are a bit softer that the steel. . . . .

Curious about the life of those Ertalyte wheels - sometimes I wonder if we can dump the wheels and replace them with solid plastic slide blocks, still on the v-rail, (like a lathe bed) . . . . .

Personally I would not give up on the wheels. The added friction that the slide block give will not be practical especially on larger machines. What I would look at is to increase the contact area. I am looking at designing an extrustion that will give about 10mm contact area on each side.
I am monitoring the Ertalyte wheels closely to see how they hold up. So far not a sign of wear. Also the machine runs very quite so it will be a bonus if they last.

Ertalyte wheels
 

Gerald,
The machine has been working non-stop for many weeks now and the ertalyte wheels dont show any signs of decay yet. They have not yet bedded and I think it might be a good alternative. The machine noise is also very low. Kobus came round the other day and commented on the low noise level so I take it must be a lot better than the metal wheels.

Marius, that is great news on the Ertalyte wheels.

Kobus's machine has direct drive motors, which makes a machine sound quite rough. I guess his comment was based on this aspect. I don't think that steel/plastic wheels will make a big difference on noise, but I may still be proved wrong. :-)

Gerald,
Many many hours later - the machine works very hard and every day. Still no sign of the wheels giving up. I cut many multi layer 3D moulds from foam. The foam tends to stick to everything due to static. The jobs are mostly 12 hours plus.

Ja Marius, even if this machine is kept simple, it still is a workhorse. Thanks for keeping us posted on the wheel life.

Does the sticking foam build up so far that it stops the machine? (in other words, are you forced to keep cleaning off the buildup a couple of times per day?)

Gerald,
No not at all. I clean it maybe one a week. It makes small patches of build-up on the tracks. If it is not cleaned the tendency is for the muck to build up on spots where there is dirt already. So it grows. I must say that the deposit is never very thick - it seems to be flattened by the wheel and have very little effect. If a brush is fitted both side of the wheel there will be no problem whatsoever. I have not had time to fit them yet.

Marius
what size did you do you Ertalyte wheels?

Garth,
As far as I remember, we just copied the metal V bearing that was specified in the design documentation. I did not want to have problems with other items not fitting so I stuck to that size. They have been going for a long time now and they work very hard. No sign of giving up yet.

Marius,
I’am bit curious… May I ask you to share a few photos of your PET wheels ?
Are they still ok today ?
Thanks, Robert ;)

Robert,
Yes the machine is working just fine and the wheels are as good as new. I will post some pics soon.

Thanks for this reply & great to read it is still in a fine working state !
BTW, next time you post those photos, tell us more about how you managed to make the inner race bearing hold ?
Robert ;)

Nylatron or Ertalyte ?
 

Copied from here:

Gerald, in regard to this post, can one make wheel with Nylatron ( BTW, Nylatron is nice stuff in my experience & opinion...machines well with most woodworking tools ! :) ) ?
I’ve used UHMW, HDPE, Nylatron…but Ertalyte ??
Intimidated by this material I’ve never heard of :o
How can it compare vs Nylatron for this V-wheel application?
Regard, Robert

I have very little experience & knowledge of plastics, so I would rather not say which will be a better plastic wheel. Nylatron looks and sounds good, but I really have no idea. Personally, I am slightly surprised that the Ertalyte is working so well, but I did realise that us DIY CNC'ers are getting too fussy about super-hard wheels (and rails).

Robert,
It looks like I managed to displace my CAD drawing of the part so I cant attach it. The bearing was press fit and we cut a groove for a retainer circlip that fits exactly on the bearing. I attach a drawing of one of the other parts that make use of the same concept.

Thanks for the reply, Gerald & Marius.
Marius, you got my curiosity & interest hooked, looking forward to see those !
Thanks a lot, Robert ;)
(Gerald, thanks for placing my post here !)

regarding the PET (ertalyte) V wheels, do the plans allow for a circlip at both sides? or you made them wider than the metal ones to allow them?

We made them wider to hold the clips but the diameter is still the same.

Found this data sheet on-line.

This company sells 2 inch dia 4 foot rod for $77. This would be enough for 64 wheels.

Why use the bearing at all? Drill the wheel for a shoulder bolt and let the wheel ride on the bolt.

Quote from Quadrant
"It is also ideally suited for applications involving soft metal and plastic mating surfaces"

John, there is a lot of side loading on the wheel. If you put the wheel between lots of sliding surfaces, there is a real danger it will bind up and decide to slide on the rail instead.

It is my understanding that(Ertalyte, PET ) is in the acetel (Delrin family ) only better because of it's ability to resist moisture absorbtion ( although very low anyway) I believe delrin would work as well at alot less then PET. I have made machined parts out of both mat'ls for years.
One more note from comment above. Statement about Nylatron, have made many many camfollowers out of this mat'l which is about a 1.5" ball with a .5" x 1.5" shoulder bolt and they run quite some time with not alot of contact and a very heavy load... although I also think in this application bearings are cheap.
( Have also had them seize up and slide along on O.D.) I also do not recommend running them on a standard bolt if that was what you were thinking. you would want a shoulder bolt

Hi Marius, I am in the process of sourcing my V-Rollers, and was wondering if yours are still holding out well? Where did you get the Ertalyte from, and will any engineering shop be able to machine it for me?
Thanks, Jonny

Jonny,
The rollers are as good as the day we made them. I am just busy converting the machine into a plasma cutter.
Any engineering shop will cut the rollers for you. Ertalyte machines very easy and they should just copy the standard v-rollers. As far as I remember there is a drawing of such a roller with the data pack.

You should be able to acquire Ertalyte from any plastics supplier. I don't know where you get it from as my engineering shop got the stuff on my behalf. Most of them should know the product.

Thanks Marius, good luck with the conversion. I managed to source the Ertalyte from Quadrant Engineering in Cape Town - less than R600/m and you can order in multiples of 100mm, so I think this is a really good option.
Cheers, Jonny

Hi, I ended up buying a nylon rod over the Ertalyte under the advise of the salesperson - he said it would be harder wearing, and cheaper. With Ertalyte apparently it is more expensive because of other chemical properties that were irrelevant to the application. Does anyone have a second opinion on this, as I can still swap it back to Ertalyte?
Also I was wondering how do I monitor the wear on my tyres - will it be obvious to the naked eye, or do I need to somehow measure it with a vernier and right angle?
Regards, Jonny

Jonny,
I would not use nylon as it does not have the same properties under pressure as what the Ertalyte has. My bet will be that the Nylon wheels will be done with much faster that the Ertalyte. At the time of going this route we did a whole lot of research and the common consensus was that Ertalyte was the best replacement for the steel roller.

On second thought, I don't think the salesman has a clue if he advised you that nylon will be harder wearing than Ertalyte. If you want I will dig the specs up to prove. Actually Nylon is not an option.

Nylon isn't that stiff...

I thought I would give some feedback on the V rollers made from Ertalyte.
The machine has now been running for almost a year as a plasma cutter. It has been used a lot. I did fit a water pan underneath so the dust is limited. The wheels are still just as good as the day they were made. The stuff is amazing.

I am busy with a new machine, even bigger than the first and I will definitely fit Ertalyte rollers again.

This time I am going to try Red Loctite (Stud Grade) to hold the bearings.

You might want to check with Loctite as to the application, they have tech sheets for most products. I know of a few cases where Loctite ( Blue 242 in this case...) caused failure in assemblies with plastic components that were chemically compromised. I am sure they can recommend a urethane or epoxy that will work.
Thanks for your updates on this option, I plan to try this when I (eventually) build.

John,
I actually changed my mind about the Loctite and designed a V roller with a 2mm rib in the middle. Now the bearings are held in place by the bolt and washers. As my new machine will have a slight adjustment in the Y axis of the gantry, the slightly thicker wheel will not matter. I have a feeling the thicker wheel will fit into the standard Mechmate design.

You don't need to machine a ridge in the middle as it needs both side machining, just make a hole and then add a recess for a retainer ring

http://www.daemar.com/images/lg_RetainingRings.jpg

loctite 648
 

I used loctite 648 "bevestiging met hoge sterkte" this means mounting with high strength. I mounted my bearings and gears with this. I made a mistake with my gear on the axis from my motor reduction and had to remove the gear.
I try to do this 12 hours after I mounted. I had to heat the gear and used a 2 ton press, an extension piece on the arm of the press and and I had to clamp the press to the table with some glue clamps. Finally I could remove the gear from the axis. but I could still feel my arm muscles next day. I didn't expect that it was that strong. and yes I have office job......
somebody used pertinax for guide wheels?

My previous set was made just like that. I want to simplify. I have to turn the unit over to machine anyway.

Take a look at MakerSlide project. It is an "open source" mechanical project. They make an aluminum extruded with integrated v-rail. Carriage move on v-roller / eccentric cam spacers / roller bearing. I'm wondering where the designer got the idea :confused:

http://www.kickstarter.com/projects/...bearing-system
http://www.makerslide.com/

BTW it could be an excellent source for Derin vroller and eccentric cam spacers.

They say that the biggest compliment you can pay someone is to copy their design.

The idea looks good but I have to say that I believe that those kind of bolt together assemblies are not good enough for serious production machines. My experience is that if you want a clean and accurate cut the machine must be very stable. No rattles and vibrations. The heavier the workings are the more stable.

That target DIYer and small lightweight slide, not heavy duty medium power CNC machine. Some have use it as a camera slide JIG for example.

found a "MakerSlide Store"

$1 Double Bearing Delrin V Wheel
$2 Eccentric Spacer

unfortunately they are almost half the size required (5mm x 16mm x 5mm bearing)

http://store.makerslide.com/index.ph...jiltne355s1tv7

I can see the advantage of plastic wheels, especially when used with aluminum rails. The plastic used doesn't have to have low friction properties. Very low friction might cause the plastic to slide rather than roll. Plastic would mean less wear on an aluminum rail, but on a steel rail, wear to the plastic could occur. Plastic is easy to machine, a +.