Solving grip problem with Link Treads

[Jim]

I have been building some models with Link Treads lately.

http://www.bricklink...tem.asp?P=57518 (new style)

http://www.bricklink...Item.asp?P=3873 (old style)

A huge problem, you all will recognize, is that the Link Treads terribly lack in grip. I have built a rather heavy NXT model and running the motor will cause the treads to slip. One solution is to gear the model down or reduce the motor speed, but that's not really a solution.

Wouldn't it be great if the new Treads were made out of rubber or have a seperate a rubber part to put on the Tread (there are two holes).

Does anyone know another solution for this problem? Maybe there are some custom parts to fit to the Tread or something.

I have been thinking about using pieces of Ducked Tape to increase the grip, but they will wear down and it will look terrible. Maybe it's an option to apply a rubbery type of glue to each of the links or using the Double Rubber Flexible Connector in some way.

http://www.bricklink...tem.asp?P=45590

Edited August 8, 2011 by Gekke Ted

[imajor]

This worked for me nicely.

[Jim]

This worked for me nicely.

Awesome! You da man!

Why didn't I think of that?! So simple, no non-Lego parts, no gluing, no destruction.

Do you have a Bricklink part number for the rubber bands? To make sure I have the right size.

I am not sure which ones I need:

http://www.bricklink.com/catalogList.asp?catType=P&catString=229

Edited August 8, 2011 by Gekke Ted

[Jim]

Does anyone know the dimensions (in mm for example) of a Technic hole? Or even better; is there a site with Lego Technic dimensions?

[Milan]

That is probably the non-LEGO rubber band.

But you can use the one that LEGO is producing as well.

[Aqualize]

Awesome! You da man!

Why didn't I think of that?! So simple, no non-Lego parts, no gluing, no destruction.

Do you have a Bricklink part number for the rubber bands? To make sure I have the right size.

I am not sure which ones I need:

http://www.bricklink.com/catalogList.asp?catType=P&catString=229

Well the linked page says that they are not lego rubber bands. Seeing the prices on bricklink for single rubber bands and comparing to a store with 100pcs pack I will not be so religious about using non "official" parts. It is not like we use a big rubber band to build a big catapult, just replacing a comparable rubberband with non-official that are a lot cheaper.

[Jim]

Well the linked page says that they are not lego rubber bands. Seeing the prices on bricklink for single rubber bands and comparing to a store with 100pcs pack I will not be so religious about using non "official" parts. It is not like we use a big rubber band to build a big catapult, just replacing a comparable rubberband with non-official that are a lot cheaper.

I totally missed the link. It's Monday

You are absolutely right about getting cheapass bands from a different supplier!

[DLuders]

Does anyone know the dimensions (in mm for example) of a Technic hole? Or even better; is there a site with Lego Technic dimensions?

Here is a PDF document that has Lego Dimensions; scroll down to the bottom to see the Technic holes. The internal hole diameter is 4.8 mm.

[Jim]

Here is a PDF document that has Lego Dimensions; scroll down to the bottom to see the Technic holes. The internal hole diameter is 4.8 mm.

Nice DLuders! Thanks!

Still thinking about molding some kind of rubber overlay for the link treads, with a sillicone based kit or liquid rubber or something. The elastic bands are a great and simple solution. However, a rubber "plate" the size of a tread would probably work even better.

[DLuders]

@ Gekke Ted: If you look at the parts shown on this Bricklink search page, you could consider pinning the 2989 "Technic, Brick 1 x 4 with Bumper Holder" parts onto the Technic Treads, and then slipping the 70961 "Technic Rubber Bumper 2 x 4" parts onto the bumper holders:

[Jim]

@ Gekke Ted: If you look at the parts shown on this Bricklink search page, you could consider pinning the 2989 "Technic, Brick 1 x 4 with Bumper Holder" parts onto the Technic Treads, and then slipping the 70961 "Technic Rubber Bumper 2 x 4" parts onto the bumper holders:

I did see this solution in the previously posted article. It will result in a tread with a lot of grip I suppose. The downside is that it won't fit many existing models.

I am currently investigating the possibility to let a rubber molder fabricate rubber pads to attach to the sides of the tread.

Something like this:

Do you think this is feasible?

Edited August 8, 2011 by Gekke Ted

[DLuders]

Do you think this is feasible?

Yes, it is feasible. I (for one) am not "hung up" on using 100% Lego all the time. The "Lego purists" out there may object, but it's YOUR model. Go for it!

[Jim]

Yes, it is feasible. I (for one) am not "hung up" on using 100% Lego all the time. The "Lego purists" out there may object, but it's YOUR model. Go for it!

Exactly. There are rubber axle connectors (used in the NXT for example), so why not have some rubber pads to increase the grip and additionally protect your wooden table or floor.

I will look into it and make an appointment with the molder to see what the options are, and of course what the costs will be. I can imagine more people will be interested if it's a working and not too expensive solution.

I have an alternate design which might work too (on the right, not sure it will be better)

Edited August 8, 2011 by Gekke Ted

[Out of Sight]

Yeah I've always been fascinated with link treads in a Technic model. Forgive me for asking, but will a grippy treads lead to 'difficult' turning, ie more effort required to overcome the grip since these caterpillar treads skids to turn? The last time I saw 30 tonne excavator's treads, they're all steel without any sort of rubber, which is why they leave typical scuff marks when ran on pavement. Idk, just a thought tho..since they're mean to grip on soft soils.

[Aqualize]

Yeah I've always been fascinated with link treads in a Technic model. Forgive me for asking, but will a grippy treads lead to 'difficult' turning, ie more effort required to overcome the grip since these caterpillar treads skids to turn? The last time I saw 30 tonne excavator's treads, they're all steel without any sort of rubber, which is why they leave typical scuff marks when ran on pavement. Idk, just a thought tho..since they're mean to grip on soft soils.

On the linked technicbrick blogpost they showed a video with the rubber band trick on the threads running on a glass surface and it seemed to have no problem turning. if the whole links are covered in rummer might be different but think of all the RC toys that has rubber threads and they work.

[Out of Sight]

On the linked technicbrick blogpost they showed a video with the rubber band trick on the threads running on a glass surface and it seemed to have no problem turning. if the whole links are covered in rummer might be different but think of all the RC toys that has rubber threads and they work.

I see..LOL, because all these times I've been 'driving' my 8043 on my bed or short carpets, so grip has never been an issue. Although the rubber band trick might kill some clacking noise when ran on hard surfaces. I should give it a try, I have a bunch of black rubber bands, so they should 'blend' with the dark grey colour.

[imajor]

Yeah I've always been fascinated with link treads in a Technic model. Forgive me for asking, but will a grippy treads lead to 'difficult' turning, ie more effort required to overcome the grip since these caterpillar treads skids to turn? The last time I saw 30 tonne excavator's treads, they're all steel without any sort of rubber, which is why they leave typical scuff marks when ran on pavement. Idk, just a thought tho..since they're mean to grip on soft soils.

I used this for a while, and rubber does make turning harder. So I'm not using it on the carpet for example.

[Brickend]

You could mould pads for the tracks, but I can see those designs slipping off, especially when lateral force is applied in turns.

Why not take advantage of the 2 unused holes in the tread?

You could take an existing pin design, mould it, and then cast it in rubber.

[Jim]

You could mould pads for the tracks, but I can see those designs slipping off, especially when lateral force is applied in turns.

Why not take advantage of the 2 unused holes in the tread?

You could take an existing pin design, mould it, and then cast it in rubber.

This idea crossed my mind. Maybe some plain rubber cilinders will do the trick too. Not sure wether it's easy to cast these pins. It would be sufficient to only cast the small end and the cap (wider band), so it will fit in the tread and leave a nice rubber cap to make contact with the surface.

And using the hole instead of pads would make it less prone to lateral deficiencies.

Thanks for mentioning this. I will get the rubber bush back on the short list

[Phantom59]

I find size "10" rubber bands ( http://www.pelikanartline.com.au/index.php?option=com_content_ex&view=category&layout=multi-view&id=735&Itemid=584 ) are just the right size for tracks. I get them from the Local Newsagent (about Aus $0.80c for 25g box) also I find a small crochet hook ( http://en.wikipedia.org/wiki/Crochet_hook ) very helpful in pulling the rubber band through the hole in the track

Warning some types of rubber bands do degrade

Edited August 8, 2011 by Phantom59

[Jim]

We are now trying if these caps will suffice!

Dimensions are:

D 8mm

d 5mm

h 5mm

Maybe the 8 mm is a little too wide, but this can of course be modified.

[Jim]

Yesterday I received two samples and guess what; they seem to be the perfect solution, even without modification!! They are tightly locked in the pin hole. And they are removable without damaging the Lego Tread Links. It's meant to be I guess

Tomorrow I will receive a few hundred of them, so I can try it on a test model. Using two pins per tread will probably also enhance the grip when climbing/riding over objects.

I'm really confident that this part will greatly enhance some treaded models. Will keep you posted. When it's succesful, I will make a short video to show the results.

Edited August 11, 2011 by Gekke Ted

[DLuders]

@ Gekke Ted: It sounds very promising! If you don't mind me asking, where do you get those "caps", and how much did they cost?

[Jim]

@ Gekke Ted: It sounds very promising! If you don't mind me asking, where do you get those "caps", and how much did they cost?

Indeed, I am very excited about this solution. Mainly because it doesn't need modifications itself, it doesn't damage your Lego and they can be easily removed to restore your tread links. And the diameter of the smaller section allows you to fit it nicely into a technic pin hole, which leaves room for other applications (base of a model for example).

Hopefully I can test it for real tomorrow. I need to build myself a simple testmodel, but I think I will manage. I will also make a short video if the results are promising.

I got them at a Dutch hardware store for about 15 eurocents a piece, depending on the volume of course. You can probably find these in the US too. If not, and if there's more interest in these caps, I can make a shipment to a US Bricklink store, so they can distribute them in the US. Or send it directly, but I am not sure what the shipping costs will be. We can figure something out. First let's see whether they do provide a real solution!

Edited August 11, 2011 by Gekke Ted

[Blondie-Wan]

I see..LOL, because all these times I've been 'driving' my 8043 on my bed or short carpets, so grip has never been an issue.

I imagine the means of driving the vehicle also makes a difference - that is, whether you're manually pushing it around, as opposed to the driving force actually coming from the treads. If you make LEGO sandcrawlers, bulldozers and tanks and just push them around yourself, I would expect the treads to slide rather than roll on very smooth surfaces, but if you motorize the models and let them move under their own power, things should be different (as long as the surface is level, that is; I think they'd still slip and slide when trying to run on inclines). But I should note I haven't actually built motorized treaded vehicles (yet, but I intend to ), so I can't speak from firsthand experience.