Forge v0.2

The forge worked OK, but some improvements were needed. The hot zone was quite small, and I thought the relatively small duct was not helping. Off came the tube elbow, replaced with a 2" tube (once the housing of a Landrover shock absorber). I joined that to the blower with some 65mm aluminium duct (actually bought for the purpose) with a tomato can as a joiner (normal service is resumed). To allow more air through, i put more holes in the tuyere plate.

I managed to get hold of some proper forge coke. Lighting it was an absolute nightmare, it took about 6 attempts. I think this is because the coke was damp. I blocked up some of the new air holes with fire cement, in case the problem was lower speed of the blast. The air still comes out over a wider area than the original version, which does seem to have made a larger hot spot. Maybe I'll open them up again one day to compare. Anyway, it seems to be working, eventually.

Success!

Finally, we have a print! Still needs some refining, but it is getting there.

One of the problems was a tendency for the extruder to jam. It looks like there is an insulator missing, which doesn't seem to be causing any thermal problem with the Arcol hot end, but does leave a large void at the bottom of the Wade's extruder where the feedstock can block up...

RepRap Heated Build Platform

I have been trying to get a RepRap working, on and off, for a few months. It was bought second hand, supposedly complete except for a power supply. Obligatory tat item: I have a spare ATX PSU, which ran the main RAMPS electronics and extruder fine, but cut out when I tried to power up the heated bed. This is apparently a known problem; the solution is to put a dummy load on the 5V rail. I tried 4 off 3.3ohm 10W resistors in parallel, it helped, but it still cut out whenthe heater cut in. The resistors got toasty though. Which made me think:

Instead of wasting the power going through the ballast resistors, use that to provide a base heater load and then have a lower power - which can be handled - on the 12V supply to give control. It needed nichrome wire in 18SWG and 20SWG. The original build platform was a piece of unetched circuit board, which I re-used, sticking the wires onto the non-copper side as shown in the diagram using Kapton tape. I think the copper should give better heat distribution, but I have no proof of that. I put Kapton over the copper and pinned it all down with bulldog clips, and it works just fine. The shorter (green) track is 18SWG, attached to the 5V supply. The longer   (red) track is 20SWG, and is connected to the D8 terminal on the RAMPS board.

Another use for a dead trailer wheel

... and an ex cement mixer - build a swift for water pipe or fencing wire. I had already converted the cement mixer frame in to a sack barrow, with limited success, so I was happy to repurpose it a second time when I needed to pay out some water pipe. A simple matter of cutting the swing arm off with an angle grinder and welding it onto the frame, then putting some cross arms onto the wheel (3x2 timber held on with coach screws).

Not only does it make unrolling the coil so much easier, it works as a trolley to move the coil about too.

Wheel Forge

I've been looking to make my own forge. I was thinking of using something like a gas cylinder, but then I found the idea of using a car wheel. I had a spare one of those so I gave it a go.
The hardest part was probably getting the tyre off. I managed to break the bead with a big crowbar, but could not lever the tyre off. Taking it to a garage seemed like cheating, so I cut through the bead and then it came off OK.
To duct the air in, I used a 1¹/₄" pipe. I had a piece with a T in it, the idea being to let the ash out easily. That was welded onto a steel plate with some 1/4" holes in, and that was welded (tacked) into the centre hole of the wheel.

Top view of the tuyere. Note the dents in the rim form unsubtle tyre removal.

Bottom view

In action

For a blower I used the heater box from a Range Rover. I simply pushed the controls over so that the air was coming out of one hole, then put a duct over that made from 3" drainpipe. The two were connected with some vacuum cleaner hose, probably about 30mm diameter, all held together with duct tape, what else. Not totally efficient but it worked.

I'm trying to get hold of some proper blacksmith's coke, but in the mean time I tried it out with anthracite nuts.  As you can see, the hot spot is small but most definitely hot. That 10mm bar is getting to welding temperature there.

(*$%&@ Drum Brakes!

I've always thought drum brakes were a pain. Why would a designer ever choose the system that is less efficient, more complicated and harder to maintain to boot? OK I know they are better for handbrake jobs.

Anyway, the brakes on the Ferrari were even more of a hassle than the usual run. I really thought for a while I was going to have to remove the drive flange to get the new shoes in. I just could not believe that it was designed such that you had to drain the gearbox and risk getting oil all over the shoes; there had to be a better way. There was no way I could stretch the springs in situ though.

After much swearing and failing, I finally worked it out. Here for the benefit of anyone else daft enough to have bought one of these tractors is how I did it.

Removing: Take off the shoe retaining springs and lower return spring. Pull the leading shoe away from the piston and place a spacer in there. Now pull the bottom of the shoe away until it comes clear of the handbrake operating bar, and hook it to one side out of the way (fig 1). This picture is taken from the offside, ie rear of the tractor to the left.

The handbrake spreader can now be withdrawn past the shoe. (fig 2)It might need a little "persuasion" to get started.

It should now be easy to detach the top spring and the handbrake cable.

For refitting, first engage the handbrake cable then fit the top spring. Then using the cunning slot in the drive flange, work the shoes roughly into place. (fig 3). (Is it just me that thinks this looks like an afterthought in the design?). Again hook the leading shoe out the way on feed the spreader bar in, engaging it on the trailing shoe.

At this point I needed both hands, so no picture, but you need to lever both shoes away from the pistons and put spacers in, to give enough clearance to get the spacer in and keep the slots sufficiently aligned. It is probably easiest to let the bottom of the trailing shoe come away from its slot. Then pull the bottom of the leading shoe and engage the spreader. Pulling the bottom of the shoe gives enough leverage on the top spring to pull it by hand, so no slipping levers and one hand free to engage the spreader.

Then just refit the bottom spring and the retainers. What was so hard about that then?

Blocked up PAS pump

A couple of weeks ago I was topping up the power steering reservoir on the Volvo, when I found out that the little paper disk that originally sealed the bottle was not still attached on one side, as I thought it was. I wiggled a finger round in the reservoir but I could not find it.

Shortly after that, the power steering pump started whining as though it was empty, but the reservoir had plenty of fluid in it. More than it had before in fact. Odd. It seems the paper disk had blocked up the pump inlet.

Removing the pump and reservoir assembly was straightforward enough, apart from the fact that three of the bolts can only be accessed though a hole in the pulley and there is only just enough space to get a socket into it. I tried rinsing the offending article out by filling the tank with oil and shaking it upside down, to no avail. According to the Haynes manual, separating the tank from the pump requires special tools and should be sent to a dealer. Yeah, right. Since when are a vice, a screwdriver and a pair of water pump pliers special tools? Having got them separated, I was able to back-flush the tank and sure enough out fell the blockage.

There is the offending item. All back together now and happy.