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Meanderer trike tilt arm

May 05, 2025 — BarryK

Last couple of blog posts for the Meanderer DIY trike project:

...the YouTube video, linked from the first post, shows the tilt-arm temporarily installed. This blog post progresses with building the tilt-arm.

I ran into three problems, so this post is also a warning to other DIYers who are not metalwork experts. In my case, far from it. Firstly, regarding tapping a thread into aluminium...

1: Thread tapping

I posted about a 3-piece tap set:

One of the guys at the Men's Shed says that he names those three taps as "tapered", "intermediate" and "plug", the last being for tapping the thread as far down a dead-end hole as possible.

I discovered that need to be very careful with using the plug-tap. What can happen is that instead of cutting nice threads, a wad of aluminium can form at the start of the tap, which then makes turning the tap more difficult. Furthermore, as the wad is wedged in the tap, it stays there when reversing the tap, making extraction very difficult and damaging the existing thread in the process.

This is really bad news. I found it best to use all three taps in turn, tapping each one as far as it will go. So, if the plug-tap has to be used, then it will have the least amount of extra thread to cutout.

I stopped using oil lubrication, and now only tap the threads dry. Reason is, little particles may stay inside, making screwing in a bolt difficult. It seems also, can make it very difficult to unscrew the bolt. Tapping dry, particles can easily be shaken out, or by blowing through the hole.

Finally, I tested screwing in a bolt and unscrewing, to verify that the thread is clear of obstructions.

2: misaligned holes

The second problem was that I ended up with some misaligned holes. Firstly, a drawing of the tilt-arm:

img1

However, when I constructed it, made a few small changes. The bottom of the post is shown as rounded; I did not do that. The total post length is shown as 141mm; I made it longer, 153mm, and changed the hole-placements for attaching the shock-absorber plates as shown:

img2

...at the top of the photo, the plates cut as per the above drawing, below, the marking to move the top two 4mm holes further up. That change does not matter; in fact if you are building from my plans, probably better to stay with the 141mm length post -- for reason that will be explained later.

Also, the drawing shows the 10mm hole at bottom of the post having its centre at 11mm from the bottom of the post. I changed that to 16.5mm -- don't know why, just did. The distance of 107mm from bottom 10mm hole to the top ones, shown in the drawing, remains the same.

The drawing shows 5mm holes; reduced that to 4mm, as decided to use m5 bolts. But, there is a problem; the standard pitch of m5 bolts is 0.8mm, requiring a 4.2mm hole to tap into. The thread tap will go into a 4.0mm hole, but with some difficulty. Solution:

Use a 11/64 inch Imperial drill bit! Actually, that is 4.37mm, big, but it worked for me. I haven't measured it, but drill bits are typically slightly smaller than their rating. Ideally, what we want is 4.2mm hole diameter.

Those 10mm holes were reamed out to exactly 10mm so that the bushes will fit without excessive force. Reamers are explained in a link at top of this page.

This is where I went wrong; the method used to align the holes, by inserting rods, was too sloppy:

img3

...trying to clamp that lot in place and drill the holes, it didn't work very well. What I ended up with is OK on one side:

img5

However, on the other side, the holes in the post are misaligned:

img6

Filling in some details:

The square post is 22x22mm, whereas the shock-absorber requires 24mm spacing. Therefore, I cutout some 1mm thick aluminium sheet as padding -- you can see it in the second-last photo above.

Those bolts are a special kind, for mounting a shock-absorber. The aluminium plates are 5mm thick, and the holes for the bolts are 10mm with brass bushes inserted, the bolts being 8mm. Here is a bolt:

img7

Those brass bushes are 8mm ID, 10mm OD and 6mm length (15-10x8x6; the 6mm is total length including the flange), purchased from here:

https://www.aliexpress.com/item/1005005073792086.html

The "bolts" are 40mm solid rod (M6x40x8), bought from here:

https://www.aliexpress.com/item/1005004989898480.html

The m8 washers are 1.5mm thick ...just the right thickness, so the thru-bolt can be tightened up without pressing the plates into the shock-absorber.

Note, the solid-rod-bolts I have used are general purpose, cheap, not necessarily used for shock-absorber mounting, though they seem OK for that purpose. If you want premium, there are special titanium ones available, used in motorcycles, for example:

https://www.aliexpress.com/item/32870612456.html

...available in 42mm rod length, which would suit 6mm thick plates (instead of the 5mm that I used).

Anyway, regarding the mis-aligned holes, in retrospect, what I should have done is attach one plate, then insert those bolts and tighten them up and make sure they are symmetrical, then drill the holes into the post on the other plate.

The current situation is that I need to fix those misaligned holes. No, I'm not going to cut a new post. Instead, I bought j-B Weld epoxy:

https://www.altronics.com.au/p/t3008-jb-weld-high-strength-metal-filled-epoxy-adhesive/

img7

...a product from the USA!

I had previously bought something similar; however, it is not strong. Very weak and brittle (for the record, it is "metal repair" epoxy I bought from here. It is sold all over the place, including eBay and AliExpress). After some research, discovered j-B Weld. There are videos on YouTube that show how strong it is.

So, I'm going to fill the misaligned holes and re-drill and re-tap them. At final assembly, going to use epoxy resin to permanently lock the plates and bolts, so can never shake loose.

3: Locking the tilt-rod

The tilt-arm hinges on a 10mm diameter stainless steel rod. The tilt-arm has to be locked to it, so that when the tilt-arm tilts, so to will the rod turn. We do not want the rod to slip!

I was a bit naive, and tapped for two m5 bolts either side. This photo shows one of those m5 holes:

img8

The problem is that having two m5 bolts either side of the rod, does not tightly lock the rod to the tilt-arm.

What is needed is a bolt from the underneath of the tilt-arm, to push the rod firmly against the tilt-arm inner wall, and then can follow-up by screwing in the m5 bolts. However, this 22x22 square tilt-arm already has a 8mm diameter hole right through its length. I purchased it from here:

https://www.aliexpress.com/item/1005004854415047.html

If you had purchased solid square rod (for example, 20x20 from Bunnings here in Australia), then you could drill and tap whatever thread you want, but I have to work with a pre-existing 8mm hole. So I thought, why not use a m9 bolt with 1.0mm pitch? OK, except m9 is nowhere to be found in Australia. I found m9 bolts with 1.0 pitch, also a matching tap, on AliExpress, so have those on order.

Yeah, I could have drilled and tapped for an m10 bolt, but didn't want to increase that hole so much bigger.

It will take a couple of weeks, and when finished I will append final details to this blog post, or link to a follow-up post.  

Tags: light