James' R5-D4: Treadwell WED-15-77: Part 25

March 09, 2024

Treadwell WED-15-77: Part 25

March 2024

I started this build back in November 2021:

Link to part 1 and now it’s coming to be completed this year 2024.

I will be creating a page viewable via the top tabs (PC) or via the drop down menu on your phones which will have links and photos to these posts.

This month:

Spray Painting
3D printing
Rubber track moulding (YouTube)
Re-assembling
Electrical installation and testing

Painting the base:

I stripped the base of everything not made of wood lol, a pain, but it means I don't have extra weight and also I don't have to worry about something getting knocked by accident.

I then masked off the paint I wanted to keep and sprayed the bare wood with primer.

Some of the area's not sprayed are because these are going to have panels covering them, as painting neatly wouldn't of been easy. Here’s the masked off areas, spray primer work.

Once happy with the primer, I applied the blue paint.

A clear coat was going to be applied once dried, but the order didn't arrive, so this will have to be done at a later date.

Painting extras:

The one remaining wheel, plus the front wheel brackets and the lid supports, all got a coat of silver (not Plasti-kote) paint.

Also sprayed up were these missed wheel bushes and the mast base support.

Servo connections: block plug or just loose.

(Planned work, now next month’s schedule)

Tracks:

Ordered a single batch of two part mix of the mould mixture, to create the tracks with. I thought, if I need more, I can buy more.

The new track mould I printed last month didn’t print out very good (lifted off bed so not flat). Later, after a few failed prints, I found that the nozzle wasn’t as clean inside as I had thought, even with hot and cold pulls. So I didn’t reprint it as I already had two moulds anyway.

I used my original moulds (green filament) ones. Dusted with talcum powder as a release agent. I had seen this done, but don't think it works too well in this application lol. Read on for what I eventually used.

Here are the track moulding in progress. I made a video of this now up on my YouTube channel.

In the video, the track that couldn’t come out of the end of the mould was due to the filament that didn’t have support and had sagged, so the fluid mix was absorbed into it, bonding it together.

This part of the mould has been removed (cut out) and sealed with superglue.

Only one of the two mouldings poured, cured, bit disappointing really and don’t know why?? = after a few more attempts, I figured out that the mixture wasn't mixed properly and so hadn't cured properly.

Here is the joining plate with two ends, of already moulded track in position. Mixing up and pouring into this, joining plate, joins these together.

The poured join. Inside doesn't look great, but that's not important.

This was another poured moulded section.

Here is all the track made so far, these will all be joined when the second delivery of mix arrives.

The mixing and moulding process improved as I went along. I now have enough moulded to complete one full set of tracks, but will have to order a second batch of mixture.

Guide teeth:

I did have a go at moulding a ‘guide tooth’ onto a piece of track.

This first attempt, didn't work. The rubber didn't bond to the back of the track like it does with the joining sections, as I had expected. Once released from it's mould, the thickness (height) effected it's ability to flex with the thinner track when moving over (around) the drive wheels at both ends. So am going to have to look at something else or another mould idea.

Glue:

I did find and test out some special loctite glue which can be used on rubber.

This seems to work, still testing, but this could be what I need.

Mould Release:

Here’s the mould release agent I used, found a can in work:

The following picture was the last of the mix I had to bond together two pieces of the track. The rest went into one and a half track mould.

Video of the track coming out of the mould on my YouTube channel.

Test laying the track on the wheels:

Re-assembly:

As the build progressed, little snags appeared. One being my choice to use nylock nuts and washers to secure the front wheel brackets. The protrusion restricted the required clearance and they would catch on the inside face of the wheel.

Plus i needed to trim the bolts down in length, and use normal nuts with thread lock.

Not to waste the nylock’s, these were swapped over on the mast base support bracket.

Electrical:

I needed to move the power switch to the outside panel for ease access. This meant unsoldering the switch on the panel, adding a new plug connection and fitting the switch into its new location.