M4 suspension progress

[Clark Ward Jr]

I had a minor "failure to measure twice, cut once" incident, resulting
in 24 pieces of tool steel that were 1/2" too short in a critical
dimension. These will be saved for 1)another project and 2) a
reminder of said incident. I substituted in a larger section aluminum
bar for the suspension arms, measured thrice and cut once. It works
well and is a heck of a lot easier to work with than tool steel... I
have 1/3 of my suspension done, minus the spring mounts. The linked
pics show the two forward port-side stations. The black material the
tank is on is the treadmill belt that will soon be cut...

http://i169.photobucket.com/albums/u224/tugboat706/Susp01.jpg

http://i169.photobucket.com/albums/u224/tugboat706/Susp03.jpg

http://i169.photobucket.com/albums/u224/tugboat706/Susp02.jpg

--
Clark in Georgia
M4 Sherman

[Steve Tyng]

Clark,

You may want to consider making those keystone shaped pieces your
swingarms are attached to out of laminated plywood. The fast growth
timber you used isn't particularly strong the way you have it
oriented. I can see the the bottom section snapping off where the
bolts go through with a strong side impact.

Steve

[Clark Ward Jr]

I had thought about doing it with laminated ply, but was short on it
and tight on cash. I will go get some plywood and do it with ply, as
building a whole tank around weak suspension is asking for
heartbreak...

[Tango71]

I like the Ferrari flag in the background

On Jul 2, 6:23 pm, Clark Ward Jr <ki4...@gmail.com> wrote:
> I had thought about doing it with laminated ply, but was short on it
> and tight on cash.  I will go get some plywood and do it with ply, as
> building a whole tank around weak suspension is asking for
> heartbreak...
>

[Chrysanthos Kanellopoulos]

Clark,

Sherman was my absolutely favorite a few years ago. Good to see one here. I
will have to agree with Steve. Perhaps you want to re-cut the keystone bogie
blocks out of successive aluminium sheets?
Also, what holds the swing arms in place? How are the springs mounted on
them? It seems you could add a piece of very strong rubber or a plate spring
in the little area where they join, though the leverage is huge there. Or
just connect the swing armplates from underneath with very strong springs.?

Chrys

[Clark Ward Jr]

@Tango: It's my 'race flag'... I like to go to the Petit Le Mans
(used to go every year); every year that I'm there, I get the Ferrari
drivers to sign my flag, which then goes on a longish PVC pipe
flagpole at turn 10 where they can see it during the race :) Got
several years' worth of sigs on it :)

@Chrys: Hehe... I love how long the Sherman has served; still in the
Chilean Army, armed with a high velocity gun from Israel. With all the
variants, I can do lots of different things, too; the way I am joining
the upper and lower hull, I can swap out the combat section for an
engineer vehicle upper :)
I don't have a local machine shop to cut aluminum for me and I'd
have to order the aluminum itself unless I cut it from 1/32" (.8mm)
sheet stock, which would take a while with 6 suspension stations, each
30mm thick...

In theory, I can cut aluminum up to 1/4" (6.4mm) with my jigsaw,
although it's a very slow cut. I have heard that it is possible to
cut aluminum with a tablesaw, although with the short cutting
distances involved, I'd worry about kickback of the work piece. I
have an old bandsaw but no metal cutting blade for it (although I
could buy one), and no assurance that it works. I'd like to improve
my shop, but that will have to wait until September when I begin
working full time as a nurse and make more than my part time medical
tech job does now. Then I can get a proper freestanding bandsaw.

I think the shortest-path to completion (with acceptable materials
strength) is to go with the laminated plywood (since I have enough
1/4" 5-ply marine grade plywood on hand) for the mounts. I appreciate
everyone's help and advice! Chrys, lest you think that I don't value
your input, the M60 IS going to run the 4" wide hinge tracks. Sending
out to get the drive sprockets made was just too expensive at the
moment :)

The current plan for the springs on this suspension is to drill the
swingarms for a screw to mount heavy springs on between the arms, as
you suggest.

[Odyssey...@aol.com]

looking at your 3 pictures, i am curious as to how freely the suspension arms move. i see the bolt head, then the arm a washer then the wood block. i would think that the bolt holes would be sightly larger than the bold and either have a bushing with a lip (?) or a piece of tubing (brass) to allow the bolt to move easier allowing for the suspension to move more freely.

 

are you making the nut and bolt tight so it doesn't come loose, but makes it harder for the support arms to move? what about using one of them mixed nuts (not sure of the proper name) where they are metal on the outside like a regular nut but on the threaded inside it's like a hard nylon. they might allow for the nut to be tight, but not where you have to crush everything between the bolt head and nut, or just double nut it.

 

Chris,
Odyssey Slipways

[Clark Ward Jr]

Yeah, I will be using locknuts of some sort for the final assembly so
that the arms can move reasonably freely.

> _Odyssey Slipways_ (http://hometown.aol.com/odysseyslipways/index.html)