Tuesday, 25 October 2011

Ball joint assay

Just tested assembly of one of the ball joint adapter plates, so far so good!

Tank Inspection Hatch Cover

I think this is the last part I need to machine for the hydraulic tank, although I have yet to machine the filler breather holes as I need to pressure test the tank first.


Spent the afternoon tapping a total of 96 holes (without a tapping head) in the foot adapter plates, really dull but job done.

DIY Hydraulic Filtration Unit

I have nearly finished my DIY filtration unit, I have yet to add the power switch but otherwise its pretty much complete. I was shocked at the price of these things, starting at about £1200! So I decided to build one out of parts I already had. I did have to buy the lift pump, which cost £150, and the 10 micron filtration unit at £25 plus carious hydraulic fittings probably another £25. The fold-up pallet truck I found in a skip. The 24V 12A supply I already had. The unit works really well and doubles as a 20l drum carrier. In fact the drum is needed as the pump and filter tend to be rear heavy!

Monday, 24 October 2011

1.5" SAE adaptor Face Skim

I forgot to skim the face of the 1.5" SAE adaptor, and so decided to re-jig it and take a 0.1mm skim off the top to give a better surface finish. You can see in the video below I held the piece in an MDF negative jig, which is anything but ideal! but with such a light cut and 24,000 rpm spindle it did the job pretty well. 

Word of warning: Turn your sound down before playing the video!!

Last of the new foot adaptor plates

Here are the 2mm sealing plates for the new foot design. This is the last of the parts I need to machine, now I'm just waiting on the waterjet cut parts from an outsourced company. They should be with me some time next week.

Hydraulic Tank Bulk Head Flange

These are the last parts I have to make for the new tank design, they are just to strengthen the tank wall where the bulk head fittings pass through. I first cut them in 8mm sheet, but it was too thick for the adaptors so these are in 4mm plate.

New Tank SAE flange and Inspection Hatch

These are the 1.5" and 2.0" SAE flange adaptors that I need for the new Hydraulic tank. They will be welded to the tank.
Here you can see the two SAE adaptors with the tank inspection hatch flange.
Also got the pump back on today with the new aluminium bell housing plate.

Friday, 21 October 2011

More 3 axis parts

These are the 12mm thick adaptor plates to fix the existing ankle contact plate to the new tibia beak ring. There will be a second 2mm thick plate sandwiched between this and the sensor plate in order to seal the sensor electronics,l the only difference being the omission of the second ring of 8 x M8 tapped holes. These plates also have the ball joint attached to them with the inner ring of 4 x 8.5mm countersunk holes.

Pump Control Block Clean

I decided to tackle taking the control block off of the pump and seeing if there is any dirt stuck in it. It's not a job I've been looking forwards to, but actually its fairly simple to get the block off.
Unfortunately it was not simple getting the spool caps off from either end of the control block, as it seems that they have been fixed in place with some kind of thread lock!! So that is the end of that, I blew out the orifice with an air line and put it back on the pump. Wast of time.

Thursday, 20 October 2011

Finished Ankle Sensor Modification

Here is the finished ankle sensor modification, I got the tap to go deeper into the housing so the M8 gland now sits flush and should be sealed to IP68. I then plugged the M6 side hole with a M6 nylon bold and thread lock. The bolt was then cut and sanded flush.

New Aluminium Bell Housing

I made the new aluminium bell housing this afternoon. It was a little tricky, as I didn't have a really accurate way of measuring the steel version, and I wanted to get the alignment spot on! However, I got there in the end and the result is great.
As you can see from these two pictures the weight saving is 12.6Kg which in the grand scheme of things probably doesn't seem that much, but the machine is a little too heave, particularly at the rear end where the engine is mounted, so any saving is worth while, especially as there is still more weight to be added yet!
The finished aluminium version with acrylic inspection/tacho hatch.
The inspection/tacho hatch is so I can fire my laser tacho through the window and take an accurate RPM reading if required.

3 Axis Foot Parts

Started machining some of the 3 axis foot parts today, above are the 16mm spacer rings, and below are the 3mm Load Cell protector caps / anti-rotation washers.

Saturday, 15 October 2011

Main Pump Removed!

Well this is something I really didn't want to do, but seeing that I have the gear pump off and I would like to remake the bell housing lighter, there is no option! Also I may look at checking the pump control circuit while its off, the bosch rep thinks it may have dirt in the control valve which is causing the occasional pulsating! Hmm..

20cc Gear pump

The new gear pump arrived which will deliver a higher flow through the cooling system, and hopefully keep the system cooler! The old gear pump produced a flow of between 20 and 36 lpm, this new pump should produce 30 to 55 lpm.

Ankle sensor modification

Having stripped down the first of the four axis legs, I decided to see how easy the modification to the ankle sensor would be. This modification brings the cable out of a small M8 cable gland to one side of the housing, currently the housing consists of two parts, but I can't bring the cable out in its original position in the new 3 axis leg design, so the idea is to drill across hole through the side of the housing into the switch chamber, then drill down through the back face to break into the side hole. The cable will then go through the M8 gland, through the side hole and into the chamber. The side hole will then be plugged with an M6 screw or something similar.
So far so good, the cross hole has been drilled to 5mm so it can be tapped and plugged to M6.
Job done, I just need to tap the M8 hole a little deeper and plug the side hole, but it looks like its going to work!

Tuesday, 11 October 2011

New 3 Axis leg strip down starts

I stripped off all of the fourth axis hardware today for the right anterior leg. This is a pretty risky move, and I've been procrastinating for some time as to whether or not to do this. But the pros for going back to a three axis leg far out weigh keeping the four axis design. If however it turns out that the four axis design would have been better I can always re-instate it, with a simpler design without the need for the belt driven encoder.

About 13Kg of parts removed including the ram, should save a significant amount of machine weigh plus help with leg position control having less weight at the tip of the leg.