Workbench upgrade

This bank holiday weekend I spent a lot of time tidying up and throwing things out of our various sheds. A long overdue job. Much of the stuff thrown out was from boxes we used to move house over 11 years ago! A full Land Rover load of old cables, computer bits, paint tins and general clutter gone to the recycling centre.

Either side of that job I upgraded the lighting in the workshop to LED tubes and made some removable additions for my workbench. All in all a busy long weekend.

I designed the bench for carpentry about 10 years ago. It has a dropped centre for sawing and is slatted to make it easier to clamp various sizes of timber while working on them. This works very well for what I designed it for but is not so convenient for the small models I have been working on more recently.

I decided to make some changes. I bought a large A1 cutting mat and attached that to a board to overlay on the bench. I have also made an infill section to cover the slats so I am less likely to lose small components through the middle on to the floor.

Both add-ons just lift off. I cleared a space to store them at the side of the workshop slightly raised to avoid the potentially damp floor.

That's Lemmy, he thinks he's helping :-)

The centre section is made from 9mm ply and has battens at each end to stop it sliding along. The board for the cutting mat is made from 12mm MDF and has pins made out of cut down galvanised nails to keep it in place. Both boards are finished with a single coat of some left over quick drying floor varnish which I have found handy for many projects.

The cutting mat itself is just tacked to the board using several layers of spray mount. I was concerned that changes in temperature would cause undulations in the mat if it was too securely glued to the MDF board.

The spray mount was enough to keep the mat from sliding about and will even store vertically for a short while but I have had to use contact adhesive along two edges to fix it more securely for longer term storage.

Gothic boss

The centre of the lawn mower steering wheel broke and fell out. A perfect opportunity to adorn it with a gothic or perhaps pirate style boss.

The liquid effect is XTC-3D resin mixed with black acrylic paint.

I also discovered a new technique. The PLA plastic used for the 3D print is easily formed using a normal hot air gun.

I heated up the fingers with the hot air in less than 10 seconds and the fingers stayed pliable more than long enough to form them to exactly sit on the curved edge of the steering wheel. The idea being they are less likely to be broken off if they touch the surface.

Farm jack

It's taken a few attempts to get the model right but finally I have finished a tiny 1:32nd scale farm jack for the back of Andy's landy.

I was surprised that I could get as much detail as I have especially as the whole thing is only 60mm tall and 6mm at its widest. Only one side is any good but the other will be up against the back of the Defender 90 so it can hardly be seen.

I've had to use a trick I've worked out to stop the fine detail becoming a gooey mess.  I've included a superfluous support that is a fraction higher than the tallest part of the model.

Without it the final details are all printed in one go and the plastic never has time to set. The support forces the hot print head to move away long enough for the detail to cool down.

It's hard to see in the photo (click on it to get a larger picture) but the white one on the left is a mess while the silver one on the right has finished correctly just because of that extra rectangle.

I've used this trick on several model now.

I don't have a trick for getting all the tiny holes up the pole to print. I kept having to enlarge them and the pole until they formed at all! About 0.8mm diameter is the smallest hole that did not close up during printing.

The reverse side was a bit fiddly to clean up. I used a Dremel rotary tool with a grind stone bit and needle files. There is no detail on the reverse but it won't be seen.

The handle of the jack is made from 1mm diameter brass rod.

Discovery 2 Air Suspension Setup

The car was tilted at a slight angle. It was obvious that the rear left suspension was pumped up higher than it should be.

From past experience I know this is most likely caused by a faulty height sensor. If the suspension drops overnight it is most likely a leaking bag, if it raises to full height it is most likely a faulty height sensor.

A quick search on the Internet found a very useful blog post. I've saved this as a PDF for future use.
That article warns that an over inflated air bag risks exploding and therefore could be dangerous if the car is driven.

Luckily I had spare sensors in my stock of parts so I planned to swap out the faulty one. The instructions suggested loosening a valve to deflate the air suspension before carrying out the work however I have a Nanocom for the TD5 which can control the SLABS, so I plugged that in to lower the suspension without having to open up the compressor box.

The Nanocom can also read the settings and much to my surprise the sensor was still showing movement. Just by bouncing on the car it was easy to see the values change! Perhaps my 2 minutes of brushing away the mud from the sensor pivots had done some good.

Without replacing the sensor, I used the Nanocom's SLS calibration utility to raise and lower each side until I got both sides level. It only works with the engine running and all the doors and bonnet closed. I opened the window so I could make changes and more easily measure the heights.

It's a bit trial and error as lowering one side also slightly lowers the other so that side then needs raising to compensate. Each press of the raise or lower button on the Nanocom moved the corresponding air spring by about 1cm.

The workshop manual uses calibration blocks but I know from looking in the past that these are expensive and I don't know anyone who has them. Most people, myself now included, just measure from the centre of the wheel to the highest point of the wheel arch.

I don't know what the correct heights should be so for the time being, until I know better, I have assumed that the car should ride level and matched the rear heights with the front heights at 47cm. I have standard size wheels and tyres and normal height suspension.

When I started, the left side was just over 50cm and the right side only 46cm.

After having made the adjustments I pressed the 'Store Heights' button. It then instructs you 'To load to the ECU turn off the ignition and wait 60 seconds.' I did as instructed.

It had well over 60 seconds because it took me a while to get the cat off the roof before I could head out for a test drive. The roads round my way are quite uneven and at one point in our single track road I had to pull over on the grass to let another car past so the suspension got a good work out on the 10 minute run.

I measured the heights when I returned, while the engine was still running and both sides were still at 47cm. Hopefully that's sorted but I still have the option to replace the sensor if it should re-occur.


==

Since carrying out this work I have been told on Facebook and found on a forum that the correct height for the suspension is 61.5mm (2.42") measured from the tip of the bump stop rubber to the axle. I have been unable to verify that measurement from any definitive source.

D2 Workshop manual 99MY extract

The nearest confirmation of the calibrated size, that I can find, is the above reference in the workshop manual which indicates the distance must be at least 60mm.

I'd be interested to know if the exact size is mentioned in a newer workshop manual.

==

Defenders plural

I am making two Defender 90's not just one.

One of them is based on Andy's 90 called Joe.

The other is a truck back version because Shelley said that is what she would like. I found a very nice looking one at Bespoke Cars by searching Google images.

The models in Blender are now complete and can be assembled to make variations of the station wagon from about a 1990 to 2016 and an open back pickup truck from 1984 to 2016.

There are several variations of the Land Rover Defender and its earlier unnamed model since about 1984. I've modelled some of the cosmetic differences but not all of them.

Pre-Defender 90 from 1984
Bonnet - dips down
Fuel filler cap - Rectangular just behind the right side (UK drivers) door.
Engine air intake - Left (UK passenger) side of the wing just in front of the door. (at least for the TD engine.)
Vent flaps under the windscreen - working flaps present.
Full length roof - 3 external ribs on the full length similar to the series vehicles. [Not modelled]
Pickup cab roof - No ribs. [Modelled]

200TDi from 1990 now called Defender
Bonnet - dips down
Fuel filler cap - Rectangular just behind the right side (UK drivers) door.
Engine air intake - Left (UK passenger) side of the wing just in front of the door.
Vent flaps under the windscreen - working flaps present.
Roof - No external ribs, smooth.

300TDi from 1994
Bonnet - dips down
Fuel filler cap - Rectangular just behind the right side (UK drivers) door.
Engine air intake - Right (UK drivers) side of the wing just in front of the door.
Vent flaps under the windscreen - working flaps present.
Roof - No external ribs, smooth.

TD5 from 1998
Bonnet - dips down
Fuel filler cap - Curved top behind the right side rear wheel.
Engine air intake - Right (UK drivers) side of the wing just in front of the door.
Vent flaps under the windscreen - working flaps present.
Full length roof - 5 external ribs only on the rear section not over the cab.
Pickup cab roof - 5 external ribs. [Not modelled]

TDci from 2007
Bonnet - bulges up
Fuel filler cap - Curved top behind the right side rear wheel.
Engine air intake - Right (UK drivers) side of the wing just in front of the door.
Vent flaps under the windscreen - no longer exist, just a pressed dip.
Full length roof - 5 external ribs only on the rear section not over the cab.
Pickup cab roof - 5 external ribs. [Not modelled]

==

Downloads:
Defender 90 Blend file
Spare wheel Blend file
Defender 90 STL files (zip)
Licence attribution

My designs on YouMagine.com

Smooth PLA Prints

I've been experimenting with methods to smooth away the print lines.

There are some chemical methods available for ABS but the equivalent for PLA uses toxic materials so I'm not keen on that.

I've tried Hi Build car primer but it took so many coats and so much sanding that I lost more detail than I was happy with. This time I have tried three different solutions. Resin, normal nail varnish and household undercoat.

Nail varnish

Resin

Undercoat

I'll jump ahead to the conclusion. None of them was ideal for the models I am making but all of them had some uses.

XTC-3D Resin

I tried two resins. z-poxy Zap 30 and a resin specifically marketed for the job, Smooth-On XTC-3D. The Zap 30 is a bit too thick and cannot be applied so easily so that leaves the XTC-3D.

If you are going to use XTC-3D I strongly recommend watching the following video first. It's a bit long but has some useful tips.
https://www.youtube.com/watch?v=TPHTPQchO1M

The most important take out from the video is to spread the mixed resin thinly over a dish. I found that the working time was inadequate at less than 5 minutes from the mixing pot but using the thin layer in a dish it is considerably longer.

Space in the dish for the resin to spread out

Where I applied the resin while it was still nice and runny it worked well.

It is difficult to get right. Even when it is thin it does not always apply with an even thickness. Some areas in my test sample had insufficient resin but I can work on my technique to improve on that.

Resin was already starting to cure!

It is important to stop using the resin the moment it starts to go off. The thickening resin ruins the areas it is applied to, see the above photo!

For my purposes the resin needs to set horizontally to self level. The vertical areas pooled and had less satisfactory results.

Carve out the lost detail

The resin sets in a few hours but I prefer to leave it overnight to be sure. After about 12 hours it was rock solid. When cured it is hard and difficult to sand. I had to use a Dremel rotary tool with a grind stone bit to make much impact. Being so hard it is very time consuming to sand any tight areas without damaging some of the detail! Large flat areas are OK to work on with the rotary tool.

I tried various techniques on the finished resin but the resin is at it's best if it can be applied in one coat and left as is.

Resin took some sanding

It took a lot of care to avoid the resin flowing in to small holes and shut lines where I did not want it! After a few goes I was able to achieve the finish I was after but there was a lot of wasted resin. I could only apply one surface at a time which had to be left horizontal to self level. That gave good results.

Resin filled the detail on the side of the wing

If there was any fine detail on a face the resin would pull towards it and curve upwards or flow in. This was like shaving off 0.5mm from the detail. Not ideal but with care could be worked with.

Resin filled the steps on the bonnet

If I was making an organic shape or there was no detail, the resin would be ideal as it is just one step to a smooth surface.

Excellent on the bonnet but had to avoid the detail

With care and while the resin is still runny I have managed to get some good results on the bonnet that would have otherwise been very time consuming to achieve.


Nail Varnish

I tried two different types of nail varnish. A clear top coat and a coloured layer.

The coloured nail varnish worked well on small areas. It had the advantage of showing where I had used it and the thicker coating filled the thin layers exactly as I had hoped. Even with the brush that came with the nail varnish, I had enough control to avoid getting it in any of the small details.

Nail varnish on the door

Nail varnish dries very quickly so I was able to do three coats in only a few hours and could sand it before the end of the day. It was easy to sand so I was able to avoid too much loss of detail.

It did not work for large surfaces. Firstly the fumes started getting to me when using this much nail varnish, for me that eventually made me avoid using it. On the cosmetic finish, the three layers of uneven brush strokes ended up with the large panels looking like patchworks. This was difficult to get to a nice smooth surface. On the large panels I had to use a Dremel.

The clear top coat was not as good on the layers but I could use it to fill the fine pattern on perfectly horizontal surfaces where the coloured varnish would be unnecessarily thick.

Nail varnish did not fill the steps

The nail varnish was not thick enough for stepped areas, perhaps 10 or more coats would do it but I did not try that. Back to the resin for those parts of the model.

Undercoat

This is normal household undercoat. It looks to be a bit thicker than the nail varnish.

I applied 3 coats of the household undercoat. It dried thinner than I expected and I had to apply it generously to get it to fill the grooves. It did not self level and resulted in an uneven finish but not much different to the brush strokes with the nail varnish.

Needs more sanding to get even

It takes a few hours to dry between coats and I ended up leaving it a day each time. The result is initially a little disappointing and it needed a lot of sanding to improve things. I was removing more detail than I would have ideally liked before the undercoat got anywhere near flat!

The undercoat was easier to apply than the nail varnish, partly because of the much larger pot but had similar results.

Acrylic Primer

One last test was to check how they took paint. I was sure the resin would be OK, fairly sure about the undercoat but I had my doubts about the cellulose based nail varnish. I let each dry over night before spraying on the acrylic primer.

Nail varnish on the front half of the door works well

Resin on the far half of the bonnet fills the step lines

I needn't have worried about the primer. The resin, the undercoat and the nail varnish worked well with no undesirable reactions to the paint.


Conclusion

None of them are perfect.

The best surface finish by far was the XTC-3D but that lost a little detail. It would be the only one to use on car body panels to get a new car dent free result.

Nail varnish on one undercoat on the other

For areas round detail either the nail varnish or the undercoat would be OK but I tended towards the undercoat because it was in a bigger pot and did not have the problem with excessive fumes.
Either take lots of sanding to finish the job. That is difficult in some areas of the tiny models.