Spot the difference!

We were somewhat surprised at the weight of the four station cetop 3 manifold we ordered from Bosh. The unit weighs 6.7Kg, and as we have seven of them on our machine, that's 46.9Kg of manifold! So I started to look for an aluminium alternative. Our Bosh rep told me that they don't stock alu versions because the don't work so such high pressures as the cast iron version, however, seeing as we are only at 160 bar, this shouldn't be an issue. I managed to find an aluminium version of the exact manifold we have made by Macabor. I also found a pretty good price of £89 each, however, after some further investigation I found the Uk distributor for Macabor, and picked up seven of these aluminium manifolds for £47 each! Well happy with that, saved over £200 pounds and the combined weight of the alu version is 18.9Kg, saving 28Kg from the machine weight.. not to be sniffed at! :)

Can-Tainer Lid

I machined up a lid for the Can-Tainer today, looking pretty good I think! I struggled to find a good chassis mount RJ45 connector, so I had to use this somewhat oversized bucaneer type socket, however, it would be pretty good for the final version, as it is IP67 rated when used with the matching connector. On the final version I will loose the DB9 and VGA connector so the whole unit should be IP67 rated.

3 Phase installed

3 Phase power has been installed today, now we can get on and test the pump :), although we can only run it for a second or two, as we have no oil in the reservoir yet, only a bit left in the pump from the manufacturers test.

Waterjet CNC cut aluminium parts.. Attemp Two!

Josh takes a look at the re-cut parts that have just arrived, they are in a different league to the first batch, some of which we still have and will use. The edges on these are within 0.1mm as was originally suggested, and they are parallel! very nice, our guess is that they re-calibrated the machine??

Take a look at the finish on this piece, its very good for water-jet!

Pump Wireing & Control

I have started to wire up the DOL and control panel for the hydraulic pump. I have added an Start/Stop button to the control panel, this controls the pump to tank solenoid valve which shorts out the supply in its off state. Once the motor is started, the solenoid can be switched on using the start button which ports the pump to the main output connector. If there is a loss of power or the stop button is pressed, the solenoid switches back to the off position until start is pressed again.

Should be getting 3 phase installed later in the week so I can test things out!

The Mantis Brain

I have the PC-104 stack built with the Vortex86DX core for the brain of the Mantis. I have added an 8 port RS485 transceiver board with baud rates of up to 921.6Kbps, I don't need all eight ports, at least no yet, but it was the only board I could find that had the high baud rate capabilities, at a reasonable cost. The Vortex board will only go to 460.8Kbaud.

Installation of the serial baord in Linux was a little fiddly, but thats brobably due to my lack of Linux knowledge. Currently I only have a single port running on the 8 port board, well actually I can have any of the eight ports, but only one at a time. So that's good enough for now!

At the bottom of the stack is a PC-104 PSU, that takes 12 to 30V and delivers 5V to the stack.

I have placed the stack in an old CanTainer I had, but I will purchase a new CanTainer for the final unit, and machine the case tops with the appropriate connectors.

Hydraulic Power Pack Arrives

Ahead of schedule our three phase hydraulic power pack arrived today :) This power pack will be used for the test leg, and no doubt will come in very usfull during hydraulic commisioning. It could also be used to run the hexapod without the on-board engine, just for body moves, but wouldn't have the grunt for any serious walking. The pack is a 7.5Kw three phase unit, delivering 150bar at 29lpm. My next job is to hook up a DOL starter for the motor, along with an E-stop and interlock unit to control the on-board dump valve. This will allow for off load starting of the motor, along with the additional safety.

Next week we will get a single 32amp three phase socket installed in our unit, the pump only requires a 16A socket, but we may as well get a 32 installed just in case.

P.S. I know it looks like Josh is always doing all the work.. but some one has to pick up the camera, and its usually me, honest!

Test leg coxa chassis

The coxa chassis is close to being finished. This is one corner of the chassis, which we are using to mount our test leg to. For some reason it seems a little small when you think about sitting at the fron with a leg so close either side!!

Our first hydraulic valves

We have just received the first of out hydraulic valves from Rexroth, very nive they are too! We have two 4WREE and two 4WRPE type valves. We are hoping the 4WREE valves will be good enough, as they are a bit cheaper then the latter type.  These four valves will be used on our test leg rig.

Waterjet CNC parts... somethings not right!

It appears that there is a problem with all of our water jet CNC cut parts :(

We had the 25mm 5083 aluminium and 1.75" steel parts cut with a dynamic head water jet CNC machine. The dynamic head is supposed to keep the sides of the material within 0.1mm of square to the face. Without the dynamic head there is a much bigger draft angle.

However, it seems some of the edges on our parts are within 0.1mm, while others are up to 0.5mm! Having taken a close look at the parts, it looks as though the cutting head was misaligned in either the X or Y axis, causing this error throughout the cutting process. This error was further compounded by the steel material being poorly clamped during the cutting process and not being held flat.

Having spoken to the water jet company, they have agreed to re-cut the parts, so today much to Josh's disappointment we packed up all the parts and sent them back. We need to start a new shelf of shame, labelled "Shelf of Others Shame!". :)