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I thought I already had a thread about this truck, but all I can find is something from back in 2016 when I first put it together, back before the Great Photobucket Treason of 2017 (may broken links rest in digital heaven).  So here we go again, with a fresh thread and potentially only some rough ideas of what we had before.

So - to recap - this started life as a Super Clod Buster delivered from an overseas hobby shop (either Tower or RCMart or something) back in the old days of the late 00s.  I believe around summer 2007.  My intention has been to build a scaler from the body and a stick-chassis crawler from the axles, but life got in the way, I didn't find the courage to paint the body and the comp crawling world moved away from sticks and into something else.  The axles got fitted with 4-link mounts and axle-mounted servos and were used for a time on my TXT-1, before being consigned to a box on the top shelf for many years.

In 2016 I refreshed the axles with new internals, converted from TXT wheels back to the original Super Clod, and built a budget racing clod up around a Reign K2-3S chassis.  The end result was a bit of a pig to drive with 4S and Traxxas 550 motors, and again got consigned to the shelf while I tried to work out what to do with it.

Last year, one of my first projects with my 3D printer was to make up some new servo mounts.  These brace the servo against 3 parts of the axle instead of 2, so the transmission case screws aren't being strained and the servo doesn't flop around.  With some 20Kg servos from Amazon, and some slightly revised geometry, it finally became driveable.  However it was still a bit slow on 3S silvercans and a bit too hard to drive on 4S 550s.  On its last outing it broke an RC4WD rod-end while bouncing over the grassy field at Robin Hood Raceway.  For a while I couldn't work out why it broke, but then I took a look at the chassis and realised the geometry is all wrong for racing.

You see, up until I started watching Trigger Kings videos a couple of months ago, I had no idea what a racing clod should actually look like.  Now that I've been educated, I see I was still building my rigs like comp crawlers.  Steep angle on the bottom link, horizontal top link, high middle for ground clearance and don't worry over much about the steering geometry.

Now I understand a bottom link should be horizontal under static sag.  For the best geometry, the top link should be parallel (when viewed from the side) and describe a marginally shorter arc than the bottom link (to maintain the correct caster angle under compression).  I don't fully understand why the bottom link should be horizontal - maybe this is where the suspension is at its most neutral? - but I also wonder if the loading on the rod-ends is reduced with this geometry.  When hitting a bump with a horizontal bottom link, the axle is free to move up and back.  When hitting a bump with an angled bottom link, the axle must move forwards (towards the bump) as well as up.  If my intuition is correct, this will increase the loading on the links and rod-ends.

As you can tell, I'm kind of running on intuition here...

Anyway - I can hardly make the rig worse than it is.  So, with that in mind, and with my old metal-clad body looking a bit sorry for itself and a completely new JConcepts 1984 F250 body sitting around doing nothing, I figured a rebuild into a classic mid-80s monster truck style is on the cards.

Righto - that is the talking done - now it's pics time!

Here's a side-on view of the chassis as-is.  K2-3S not really designed for Mod Clod builds but it's sturdy and tough.  Geometry is more crawler than racer.  Note tape around bottom links and endbells because of clearance with 550s.

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This view shows how much the bottom link wants to come down.  I measured 47mm.  Top links and wheelbase will be adjusted later.

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So, I figured the easiest way to drop the bottom link is to make an extension for the chassis.  I have some 3mm alu sheet which is easy to cut and shape.

Here I traced the bottom part of the K2 chassis onto the sheet

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Drew on some dimensions

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and duplicated the bottom part

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Two brackets drilled and cut

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Filing brackets to shape

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and fitted

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Now, there is a problem with this design.  The sharp-eyed among you will notice I haven't yet moved the top links, so the geometry isn't too good.  Ideally the top links should be parallel to the bottom, but the only mounting points would make the top link way too long and detrimentally effect the geometry on compression.  Since I've got an entire Sunday to kill every week and limited supplies coming into the house, it made sense to abandon the work I'd done so far and start again with a nicer drop bracket.

So - here it is:

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This time designed in CAD (Fusion 360 sketch to be precise), printed on to A4 and glued onto 1mm plasticard, then drilled through into 3mm alu sheet.  By this time the day was getting long, I was tired, I wanted to get in a quick cycle ride while the air was still warm and had to get showered and dressed ready for the workshop chat, so I opted to annoy my wife by leaving the jigsaw and workmate in place ready to start cutting again when I have some more time.

It has occurred to me that I have the trickiest part of the K2 chassis now in CAD format.  All I really need to add is a selection of shock mount options and cross brace mounts and I've got my own custom chassis.  It would be neat to design it with some nice swooping curves and some relief in the middle and have it made up in carbon fibre.  Well, we'll see how much that costs.

I'll knock up the prototype using my custom bracket and see if the rig handles well.  Then I'll probably have to adjust the wheelbase for the F250 body and come up with a good project name.

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You're getting into ideas that have been forming in my head. I too have been watching the Trigger King videos. But I'm oddly only interested in the retro class. So I've been having the same thoughts on geometry, but applied to ladder bars. 

 

And then I thought of a hybrid chassis. A TVP design, but for ladder bars. They seem to be the lightest and most rugged, so why not try to make them work better? 

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On 4/21/2020 at 11:15 AM, Mad Ax said:

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Apologies in advance...in my head this now forever be.. ... the Thongbuster

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Bump!  It's been a long time since I last worked on this truck, but I finally got around to it again today.  There's been a few changes to the plan, but essentially this is still a basic super clod with a home-made chassis designed for racing.

Firstly, the '84 Ford body isn't going to be used on here.  It's too big - more like 1:8 scale - and won't look right next to my other Ford monster trucks.  That's going on my E-Maxx once the weather is suitable for painting and I've got a few other spares sorted out for it.  Instead, this truck is getting a '79 Ford Super Cab.

Also the mock-up I made above was measured and loaded into Fusion 360 and turned into a complete chassis plate, which I have yet to come up with a name for.  For that matter, I don't have a name for the project either.  I'd like something swords-and-sorcery, fantasy or myth-and-legend, to fit with my other trucks...  But I'll think about that later.

So - after nearly a year sitting in the box doing nothing, where do I begin the rebuild?  Answer: by getting it out the box and taking a picture:

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It's all still there :) apart from the servos, which I borrowed for something else, then broke.

Here's my new chassis design, with top-end geometry taken from the K2-3S chassis and bottom end from my unfinished extension plate.

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I decided to build a prototype on 3mm FR4 sheet.  I cut around the template (I should have printed on thicker paper!) and marked some locating holes, drilled, then used those to hold the template in place.

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Marked out all the holes on one end of the plate.  The plates are symmetrical front to rear.

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With two sheets of FR4 screwed together using the bottom mounting holes, I drilled both sheets on one side using a 2mm drill bit.  This gives me some wiggle room for later when I'll drill out to 3mm.

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With the holes drilled at one end, I unscrewed the plates, flipped one over, screwed again, then used the existing holes as templates to drill the back end.  This way, I can be sure both plates are identical and also symmetrical front to rear.  When using an existing hole to locate the workpiece in the drill press, sometimes there's a wiggle and the existing hole goes a bit off centre.  This is why I drilled to 2mm - when I drill to 3mm later it will drill out both sides in the exact same place and I won't have any slightly off screw holes.

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Next trick is to cut the plates out from the sheet.  I put my template back on and drew around it with a sharpie.

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Then I started cutting with a jigsaw, with both sheets screwed together, so they'll come out the same.  And then this happened.

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This was an expensive (although old and well-used) bit for cutting 15mm laminated plywood without damaging the surface, so I thought it would be OK on 6mm of FR4, but obviously FR4 is much more dense than plywood and doesn't dissipate heat at all well.

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After that I switched to a different blade, but I melted that too.  Finally I found a very cheap blade for cutting aluminium, and realised I could actually run the saw very slowly and still make good progress, albeit one sheet at a time.  Eventually I had one plate cut out.

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I then bolted that to the other sheet, drew around it, and cut that out.

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Again, by screwing both sheets together, I go around the edges with a file to make sure both plates are identical.

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After doing this, I would normally flip the plates over, screw and file again, so they're not just identical but symmetrical too.  However as this is just a prototype, I'm not that fussed.  As long as it's neat and tidy and works properly, I'm happy with it.

Then I marked out the relief.  The final version will have a large relief section as marked, but for the prototype I just wanted to take some meat out.

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I used some hole cutters and lots of patience to cut out some nice big holes.

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And here it is - fitted to the existing links

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Both links stay parallel and the camber angle doesn't change much when compressed.  Depending on conditions, I might want to adjust the top link length to change the bump steer characteristics or to ensure there's still positive camber if I land a jump on the front wheels - otherwise it could get unstable on landing and flip over or veer off course.

Wheelbase is slightly too long for the '79.  The longer wheelbase was probably nicely stable, but I want this truck to have factory arches and I think they look silly if the wheelbase is too far off.

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Later in the day, after much cutting, grinding and screwing of rod ends, wheelbase is closer to where is should be.  It's still a little too long, but I'll worry about that later, it might look fine once the body is cut and mounted.

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Now, the eagle-eyed among you may have noticed that I deviated slightly from plan.  The forward-thinking might have realised why this is a problem.

Essentially, I based my chassis measurements from the K2-3S chassis that the previous version of this truck ran on.  This was just over 300mm in length.  However my FR4 sheet was just under 300mm in length.  I didn't want to end up with too many odd-shaped offcuts, so I opted to deviate from plan and eyeball the holes in the ends of the plates, moving the end crossmembers towards the centre a little at each end.  No big deal, right?  I mean, those crossmembers don't really do anything that needs them to be in a particular place, right?  And this is only a prototype.  The final version will be cut from carbon fibre and have the crossmembers in the measured place.

Well, the crossmembers are where the body posts go.  No big deal, right?  It's a new body, I can cut the holes where.  Well, I didn't exactly eyeball the holes square.  So the crossmembers are slanted, and so are the body posts.  Plus, if I cut the holes as per this design, I have to accurately measure and modify my CAD drawing before it goes off to be made in carbon fibre, and there's no way I'll measure it right.  So - basically, I can get the truck up and running, but I can't mount the body until I've had the final chassis made.  Oh well, check twice, cut once!

So - still lots more to do.  I'd like to at least run the truck around the garden before I have the chassis made, just in case there's any surprises lurking.  So next weekend I'll be trying to turn this into an actual runner.

In the mean time - here's a pic of my workbench showing a history of Ford monster trucks through the ages, none of which are finished.

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I really enjoy your build threads!  I appreciate all the pictures and narrating that you include.  It's fun to follow along and also learn some tricks at the same time.  Thank you.  :)

I look forward to seeing how this one comes together.

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10 hours ago, schlabinski said:

I really enjoy your build threads!  I appreciate all the pictures and narrating that you include.  It's fun to follow along and also learn some tricks at the same time.  Thank you.  :)

Thanks :)  In other forums I am usually accused of giving far too much unnecessary detail and waffling about irrelevant stuff :lol:

I still haven't decided what to do about my body post problem.  The chassis has come out so incredible well, and feels so stiff and strong, that I don't think I actually need a carbon version at all.  I can put the money I save into some half-decent motors and ESC.  But I still need to work out how to suspend the body!

There are some screw holes suitable for horizontal body posts, but IMO there are too many drawbacks to that style.  Maybe I'll just cut some new delrin crossmembers.

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Updates!  Sunday was a short workshop day, so I didn't have time to do a lot, but I did fit some Alturn 780 servos with Kimbro 124 servo savers, a pair of new-ish silvercans, made some body post mounts and started making a radio tray.

I started off with the truck in the same state I left it last week.

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Servos added.  M4 threaded rod used as a steering link, although a heavy front-on collision will bend even that.

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These are my own-design resin servo mounts.  They've survived reasonably well although the truck never got a lot of use.  If I could get these done in PETG they would be superb.  Mounted with two machine screws through the transmission case at the front and a single screw at the rear, so they don't twist or bend the screws like other servo mounts can.

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Now on to the body post mounts.  I figured the best option was to mount some angle bracket horizontally on the chassis.  If I ever get my plates made out of carbon fibre, I can always use the FRP plates as a template to drill my post mount holes in the exact same spot, so I don't need to worry about my body not fitting.

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Made up the post mounts from L-section

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After that, I had to retreat into the house to look after my daughter, so I took the rig with me to trim and mount the body.

My daughter has decided that she prefers the "cave" under the dining table (also my office #becausepandemic), which meant the lounge was free for me to watch my own TV for a change.  Yes, my house is an absolute state, we're renovating 3 rooms at once while also working from home and there isn't space for anything :D

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Anyway, I had enough time to get the body trimmed.

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Finally - I also have a project name!  I'm keeping it under wraps for now because I have another reveal to make once I've had time to do some painting.  There is a little hint in one of the above photos.

Watch this space for more updates.  Hopefully, assuming no more DIY setbacks, next Sunday will be a full workshop day so I can get the radio tray finished and give the truck a test-run around the garden.

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Making progress! Based on the photos, I'm thinking the truck will be Tigger, Philly, Dolly or Discarded Shoe :D

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Y'know what? This is probably the first Mod-Clod I like. Normally they look all goofy and spider-like to me, with their extrememly stretched wheelbases and pushed-out wheels, but this one actually kinda resembles an actual modern monster truck. Good job! :) 

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20 hours ago, Badcrumble said:

Making progress! Based on the photos, I'm thinking the truck will be Tigger, Philly, Dolly or Discarded Shoe :D

Ooh, the Philadelphia Experiment - I like that idea!

1 hour ago, GooneyBird said:

Y'know what? This is probably the first Mod-Clod I like. Normally they look all goofy and spider-like to me, with their extrememly stretched wheelbases and pushed-out wheels, but this one actually kinda resembles an actual modern monster truck. Good job! :) 

Thanks :) It's got the angle shocks popular on modern-ish race trucks but style-wise I wanted it to look like an early Stage 2 truck.  The shell is probably a bit pre-Stage 2 era but it's a good looking body so who cares?  I've done enough trucks over the last year (and followed enough other builds) to notice how there's plenty of scope for creative licence.

Weather was good yesterday so I started on the paint.  Still have one final colour to add today but so far it's not looking quite as good in the flesh as it did in my head, plus I'm not entirely sure my metallic colour has done on well, there seems to be lots of mottling in the colour.  Fingers crossed it's all on the overspray film and will disappear once I peel it off.

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Quick update!

So far the chassis has gone remarkably well.  I expected more problems marking, cutting, filing and generally using the chassis.  I thought it wouldn't be strong enough, or would split when cutting, or drilling, or would break as soon as I put screws through it, or something.  But no, it all went together really well.

The body, however...  Well, it's my first paint job of 2021, and a bit unexpected because we got some random warm weather this week.  I'd spent some time last weekend scribbling out ideas for a project name, which sort of dictated a colour.  Well, almost.  I knew I wanted multiple colours but it was only when I saw some photos of Alfa paint schemes over on the main page that my brain started heading in roughly the right direction.  As luck would have it, I had all the colours in stock, too.

Unfortunately I had some issues with mask bleed.  I tend to use Tamiya masking tape to do the actual lines on the body but I cover the rest with cheap tape, because that Tamiya stuff is expensive and the rolls are small.  And when I run out I have to wait 3-4 days to get more.  Well, I have to be careful because that cheap stuff can peel up, which is did this time.  Usually I'll notice it before I add my second and third colours and I'll take it off with Carson Paint Killer on a cotton swab, but this time I missed it, I thought it was on the overspray on the outside.

Also my masking job was atrocious.  Getting compound curves with straight tape is never easy but generally it looks alright once the paint's on, only this time it doesn't - at all.  I'd say it's probably the worst paint job I've ever done.  But what the heck, it's going to be a runner, I'm pretty sure this truck will roll over a lot over the next 12 months, maybe I can justify another shell later in the year, for now I just want something to run...

Here's what we have so far:

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Tamiya metallic orange, black and white, and silver backing.  I love Tamiya's metallic orange.  It looks a bit bright in the photos but in natural light it's like liquid copper.

Unfortunately, here's my super-scabby masking job.  I guess the contours in the body really make the bad alignment stand out.  I'll see if I can go over this with striping tape, if not I might mask and paint the black pinstriping on the outside.

You can also see here where I tried to mask and paint the grill in black but somehow it came out all wonky, so I cut the overspray film and put some chrome effect paint on the outside to hide it.

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Bleed on the A-pillar.  Really noticeable area and not much I can do to distract from it - options are to mask and patch the outside with white paint, or to cut some white vinyl to cover it.

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This little bit isn't too bad - I could hide this with decals.

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Overall, the finished paint scheme just doesn't look nearly as good on the body as it did in my head.  Plain red instead of copper would have been better, or swapping the white out for black and doing away with the pinstripe.

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Well - in for a penny, etc., I figured I might as well throw on the decals and see if they fix it.  The '79 is an odd body because there's no moulding to the front grille area, it's all done with decals.  They're good decals, but it means the shell doesn't look complete until the decals are on.

And then I got a short way into the job and this happened.

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Yep - the decal sheet that came with the shell includes trim lines for the side of the truck, but they're too short.  I've checked, and it's the exact same decal sheet that comes with the SWB '79 body (which I also have waiting for paint).  Photos of the Supercab body on the JConcepts website seem to show the side trim extending the full length of the shell, so I'm guessing there's been a mistake at the packing plant and the wrong decal sheets have gone in.

What's even more annoying is that the decal sheet for the other body is actually damaged.  If I'd known I had the wrong one here, I could have subbed it for the one on the other body, but I've already cut up and stuck the decals from this sheet that were damaged on the other one.  So I've mailed JConcepts and asked them if they can ship over two new decal sheets.  No reply yet and no idea how long it will take to get fresh decals sent over from the States.

Anyway, here's a few shots of the stickered up cab.  I have a sneaking suspicion this body will get filled with sand and used as an obstacle on my course before it seems much action on top of a truck :o 

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It's Easter Weekend here in the western world, and that means Friday and Monday off work.  Unfortunately because a) I have a child, 2) we have a tonne of DIY to do and iii) there's a pandemic going on, I don't actually get much real benefit from it (apart from getting some DIY done).  On the plus side, my child is so enamoured with her used iPad that she got for her birthday that I pretty much had Friday afternoon to myself to try to fix the decal problem on the truck.

Now I was pretty sure I'd taken pictures of this, but I can't find them, so I must have dreamt it.  But anyway, I had a genius idea: the decal set that came with this body was too short, and the set that came with the other body is damaged.  BUT, it's not completely entirely 100% damaged.  That means there are some good sections of side decal that I could cut out to make a join.  You can see it up close (it looks like the printer configuration was different between runs) but it's fine for a runner, which this is.

After fixing the issue with the body details, I broke out my enormous stash of generic decals and proceeded to plaster them all over the truck.  Actually, a little more thought went into it than that.  This truck is going to have a sister truck (hence why I have another '79 Ford body) so I had to make sure I had enough decals to do the same livery on both trucks.  I left plenty of space for the truck name to go on once that was printed.

Again, I was sure I'd taken photos of this process, but I can't find any, so here's how everything looked when I went up to the workshop this morning:

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My first plan for Workshop Sunday was to finish the radio tray so I can test-drive the truck.  I used some lightweight angle bracket and some 1.5mm plasticard.

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Then I soldered on some new silicon motor wires and gold-plated connectors.  Those standard bullets and plastic-coated wires are OK on a low-powered basher but the motors move around a lot on a Clod so the wiring needs to be able to deal with that.

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Then I turned my attention to the battery tray.  In a previous incarnation, the tray had sat up top and had a velcro strap around it.  This version of the truck has the tray slung underneath, so I couldn't get a single strap around the middle.  Instead I glued a piece of plasticard over the front of the tray...

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Then I cut some slots in the other end to pass the velcro strap through.

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