A Chequered Chieftain at #10

[Richard Goodwin]

Over the past couple of weekends, I've been working on the rear end mod which changes the shape of the rear end. We've seem some excellent examples of this so far using various methods. Now i was originally going to arrange to have this new plate welded in but after much consideration, I changed that view on the basis that I would have to weld both sides to get the strength and would probably have to add extra bits afterwards, to get the look I wanted. So I came up with a different idea which needs no additional extra bits other than filling and superglue to the external surfaces in order to get the look I'm am aiming for...........as shown below

The first picture above would indicate that the angled plate extends slightly beyond the rear plate whilst the second picture shows the bottom of the angled plate nestling nicely in the floor plate with the floor plate edge being finished off square.

This is how I achieved the above. Using the pictures provided by John and Stephen in their blogs, I estimated where to cut the base of the rear plate..

When the cut was complete, it was filed flat and level; later on, the bottom edge was to be filed at an angle which matched the angle of the angled plate.

In an earlier post, I described how I straightened the floor so i won't be describing that again.

Using the measurements provide by John Clarke, a cardboard template was made of the angle plate and a check of fit conducted. Any adjustments necessary were made.

Once happy, I transferred the template shape onto a piece of 4mm plate adding a further 5mm to the depth to allow for an overhang of the rear plate and to allow for any small corrections that may have to be made as fixing progressed. Using a jigsaw, the angled plate was cut out, filed flat and a trial fit conducted. Note that all edges of the angled plate were filed square to the faces!

With the angle plate in position, the cutting lines for the floor were drawn, the floor removed and the cut appropriately using a jigsaw. Note, if using a thick marker pen for the cut lines, ensure you cut on the back of the line and not the front! The floor was then finished off by filing smooth.

And another trial fit was conducted

The original brackets which secured the floor to the rear plate were then used to secure the rear plate to the angled plate after first being opened up slightly to match the angle appropriately.

The cut off pieces of floor were used as templates themselves to make identical plates but this time in 4mm plate. These two 'front plates' would strengthen the floor, provide support to the front of the angle plate and to provide a suitable level to assist with fixing brackets as can be seen in the finished pictures. They were secured to the floor using 4 M3x12 csk bolts having first had a coating of Loctite 648 on the underneath to give a strong bond to the floor plate.

On the subject of brackets, six were made from some 19x19x1,2mm cabinet fixings; they were squashed flat in a vice and then angled accordingly

The brackets, three per side, would join and secure the floor the angled plate to the front plates and the the floor plate; the end result of which is shown below

I did have to reduced the head diameter of the bolts used to secure the brackets to the rear plate and the angled plate which resides just above the overhang. This was needed to allow the angled plate to sit flush with the rear plate.

I will be changing out the normal M3 washers used in securing the cabinet brackets for M3 penny washers to spread the load more and I may consider using Loctite 648 as well to provide even greater strength. I also need to file down the overhang; I was thinking of leaving around 2mm; this should allow room for some weld beading as well. Any comments on this?

So the above is my version of how I've done the rear end mod. I probably put far too many fixings in it but I will say, it appears rock solid I'm a sparky, not a spanner so that can be my excuse

Lastly, stay safe people; its very dangerous out there right now!

[John Clarke]

That's really good permanent DIY job there Richard, time to turn it over and get on.
(I wish, there's always something else) Bum cheeks next?

[Richard Goodwin]

Not quite John; still need to file the overhang to be parallel to the ground before moving on. That said, the material for the 'bum cheeks' (4mm), is on order as is the material for the lower bollard mounts (6mm). Speaking of which, does anyone have any pictures of said mounts along with any measurements?

[Richard Goodwin]

So carrying on from the last post, the angle plate now needs to be finished off.

A red line was drawn on the upper surface of the plate marking the boundary between it and the rear plate which was subsequently removed to allow filing.

The top edge of the plate was then filed parallel to the ground such that the red line was no longer visible. This has the effect of reducing the thickness of the angle plate. Next, the rear plate was reinstalled and a 1mm sacrificial strip was affixed to the rear plate using double sided tape. The edge of the angle plate was then filed at a 90 degree angle to the ground all the way up to the sacrificial strip.

The whole rear end was then stripped down in its entirety to allow for etch priming of the steel parts to prevent galvanic corrosion as well as the inside of the angle plate. You can also see when its stripped down, how little material there is for the plate to sit on. This was necessary to achieve the look shown in the very first picture of what was wanted.

When the etch primer was dry, the rear end was reassembled and the look finished.

That was Thursday afternoon; Friday saw me merrily filing down the bottom of the hull sides thinking how I was going to support this thing once I had finished because of its curved floor now being lower than the hull sides when up pops Mr DHL with a package. I've been ordering lots lately so happy to it in without looking. When I opened the box, it was a piece of medical kit and certainly not for me! Fortunately, the address it should've gone to was just around the corner so I legged it over, whereby the recipient was very grateful. Whilst there, I noticed they had a skip partially filled and asked if I could have a poke around. I found a section of what I think is insulated plasterboard; the foam of which seemed quite firm. The power file was used to carve a rough V into its surface, quick and dirty.

With the hull sides finished

a trial sit was conducted.

The tank appeared to be rock steady and it was such a nice day, I decided today to fit some of the upper stuff for a preview

This thing is kin huge and no, the foam didn't give way so looks like I will be using it on top of some 18mm ply on the motor cycle lift very shortly

[John Clarke]

Certainly is a monster Richard and so is the extra work needed to improve the detail of this superb model.

I'm spending so much time on small details which allow other details to be achieved, it's becoming quite obsessive.

Hoping this will drop off once the hull becomes permanently right way up.

[Richard Goodwin]

Yeah, not sure that 200 hrs is right in our instance; more like 2000 hrs and then some

Anyways, today was a sunny day so decided to take advantage and prep and etch prime some of the big stuff above the hull.

I even got me washing done as well in between
Anyway, its been a long day and I deserve one of these at least before the sun goes down........CHEERS!

That's a proper gin glass btw with about 5 shots ..............what drink problem

[Richard Goodwin]

With the weather getting warmer, time to switch focus from those little jobs to the bigger stuff that needs to be done outside so I have now switched to the exhaust box.

Its been established that the height of the box needs to shrink by 10-12mm. This means cutting both the sides and the back plate as well as reinstating the rebates in the side panels. Now a mill would be really useful here; I don't have one of them but I do have one of these......

Now this will cut aluminium providing you use a carbide tipped cutter and take small cuts. The cutter I'm going to use is a 2 flute, spiral upcut bit and I will be taking 0.25mm cuts per pass. In that way, the bit isn't stressed in cutting the aluminium. It is also very important that the router has a fine depth of cut adjustment; without it, you are more than likely to break the cutter!!!

I'm going to start with cutting the sides to length and to do this, I will need to make a jig. This will enable the work to be held in position whilst cutting and also allow repeatability of results when cutting multiple parts the same. The basis of the jig will be a sacrificial flat work surface that you won't mind a few screw holes and cuts being made in it; I used an off cut of a work surface.

The next step is to place the work central on this board and surround it with a material which is the same height as the work piece; in this instance, it would need to be 12mm thick which is the thickness of the work piece. I would normally use mdf for the surround but I only had 18mm so this was reduced down to 12mm using this little number.....

Its a pain in terms of setting the depth of cut and you will only be able to cut the width of the blade with each pass (3mm) but time soon flies when get into the rhythm
Now the surround will prevent any side to side movement of the work piece. To assist with removing the work piece, two holes were drilled in the base board and then double sided tape was applied to the bottom of the work piece to give even greater security.

You can see the rebates clearly on the side panel and I will now look to reducing the height by 11mm and then reinstating the rebate that was removed. To facilitate cutting in a straight line and in the right place, I have added a 16mm guide bush to the router; the position of the guide rail (which i will run the guide bush up against) in relation to the actual cut is calculated as shown below.....

Its the diameter of the guide bush minus the diameter of the cutter and the result is divided by 2. In the picture this works out as 5.2mm so say 5mm. The forward guide rail is then installed 5mm from the cut line. 16mm from the forward guide rail (the diameter of the guide bush), I added another guide rail. This ensures the router cutter remains 90 degrees to the work piece and helps in limiting any damage due to kick backs.
So with the guides in place, a test cut was undertaken....

Note the shavings on the guide rail! Its important that these are cleaned off with each pass so have some form of extraction nearby.

With the test cut being successful, successive cuts of 0.25mm per pass were made until the full depth of the work piece had been reached. The top guide was removed and the work pushed out from the surround via the holes made in the baseboard. The second panel was pushed into position complete with double sided tape, the guide rail reinstalled and the 2nd panel was cut to length......

The next step is to put the rebate back onto the end of the panels which means adjusting the surround to the new length. Fortunately for us, the router has showed us where to cut the left side surround with the initial cuts.....

The saw was used to trim the left surround at the arrow mark and reinstalled. The work piece was placed in the surround and the bottom surround was re-positioned and secured into place. The positioning of the guide rails was as described previously but this time, the cut was only going to be 3mm and to a depth of 7.5mm. Do the first one and repeat for the second one...

The next step is to chop down the back plate by 11mm but that will need 6mm mdf for the surround and that's being delivered next week (was ordered two weeks ago).

If I was to do this again, I would use a scriber on the metalwork, have extraction attached to the router and have 12mm mdf readily available

[John Clarke]

Fantastic stuff Richard. Having to remove so much material accurately in such a way is awesome.

Just goes to show if you put your mind to it, you can achieve anything (Marty BTTF)

Now the more interesting stuff can be added to the rear end.

Problem is you've got to make it first

[simon_manning]

Ingenious, best before the 5 shots of Gin! clever thinking, regards simon manning.

[Steve Norris]

Richard
Very ingenious method used to carry out the mod, it is good to see more builds going the extra mile to achieve a more accurate end product.
Regards
Steve

[Richard Goodwin]

Thanks for your more than generous comments gents. It was a challenge but definitely worthwhile; I so hate filing and this way avoids that. If anybody is interested in using this method, you’ll find the following link really useful. I picked up loads of tips from it:
https://m.youtube.com/watch?v=-gboj2XhuW0

Yes I know about the small stuff John; am not looking forward to that either which is why I’m delaying doing them

The gin came after the event most definitely Simon.

[Richard Goodwin]

Carrying on with the exhaust box, the result of the routing required that 4 fixing holes in each side panel needed to be drilled and tapped appropriately. The rear plate would also need two new mounting holes for the bottom fixings...

All the exhaust fixing holes were then on all the flanges and the panels themselves were filled with an epoxy resin, the reason being that the exhausts are held on with three bolts each, not six and that I would be replacing the securing bolts with M2's instead of the supplied M3's. in addition, the GUE exhaust outlet hole was also filled since this would be moving such that the rear most part of the GUE exhaust flange would be in line with the rear most part of the main exhaust flange as you can see here in the picture below.....

General pic.jpg (137.74 KiB) Viewed 2011 times

To assist with filing the GUE main hole with epoxy, the top panel was installed which closed the open hole up and gave a larger area for the epoxy to bond to. Once dry, the epoxy was sanded down using in part, Phil's tip of fixing a sheet of abrasive paper to the worktop..

The fixing holes for the main exhausts were then drilled for an M2 clearance.

I can't do anymore with the main box now until I get that 6mm mdf for the front panel so I changed tack and attacked the affectionately known 'bum cheeks' shown below...

Apologies if I get the terminology wrong but when you compare the thickness of upper lifting lugs with that of the towing bollards, the towing bollards look thinner. Compare the towing bollards with the bum cheeks thickness and the bum cheeks are thinner still. Now the supplied lifting lugs are 8mm thick so my towing bollards will be made in 6mm and the bum cheeks in 4mm. So the first point of call was to try and get the shape of the cheeks which follow the contours of the gearbox. With the gearbox in position on the hull plate, a line was scored on the gearbox where the hull plate ends. An appropriate piece of card was then taped along the line and the outline of the gearbox drawn on the opposite side....

This template was then used to cut out two cheeks, one for each side. These were fixed to the gearbox using two M3 CSK screws. The cheeks were then filed down carefully using a powerfile until they matched the profile of the gearbox and were level with it. The holes were then filled with P38 filler, sanded down and etch primed.

Whilst the hull plates were off, i decided to check and adjust their straightness; its weird how this stuff can warp if not fully supported and yes, they were straight beforehand

It's Gin o'clock time so CHEERS everyone; hope you are all keeping safe and well.

[Richard Goodwin]

A general question to the forum: can anybody recommend a good strong adhesive for bonding metal to metal?

VMT

[Vince Cutajar]

JBweld. Not JBkwick. At least that would be my go to adhesive.

Vince

[Richard Goodwin]

Many thanks for the quick reply Vince. Anybody else have any other suggestions?