Deathly Hallows - FW - Alligrater

[Ocracoke]

Soldering is a bit of a faff I agree - it is a matter of waiting a few minutes to get it really hot and then feeding the soldering in. Solder with flux corded stuff in it also helps.

[Deathly Hallows]

Been a few days since my last update.

I have been working on the chassis. A tubular frame inside the HDPE is now partly assembled.

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I am bolting it together, and then bolting the HDPE armour and floor to it. Should be pretty solid. I am away working the next two weeks so no chance to work except at weekends.

The list of tasks is long and timemis getting short before Grantham which I hope to participate at. But I have no doubt I can get a ram bot working at the very least. A self righter and an active weapon is still my aim. Though with two high torque MY1016 motors it will still pack a punch of at least a push - lol

[Deathly Hallows]

Spent hours in the garage this weekend working on the robot, but when imlookat the photo I wonder where the time went?

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A lot of time did go in bolting together, measuring and marking and the disassembling to cut or drill and reassembling for the next measurement. Due to movement and the limited accuracy I can achieve in working the materials I thought this the best practice.

The linear actuator arrived, just waiting on mounts.
Got almist everything I need for a running bot now, just need to assemble it.

Will weigh it after I have it running with motors and self righter and see if I can add an active weapon.
I am also wondering if I can fit a articulated tail ii like use as a club to fit the Aligator theme. But only if I have time.

[Deathly Hallows]

Busy today
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I used a small piece of angle as a horizontal strut brace at the front. Simply used the Dremel to cut some slots and filed the angle a bit before forcing it home. Increases stiffness a lot.

The vertical white HDPE is bolted ing. These will hold the fixed axle.

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Weighed in at this stage and 9.9kg! Oops. Never mind an active weapon this is going very tight. Some holes (which I will claim are for ventilation later) will be needed.

[Deathly Hallows]

Some notes on the other parts of the build.

I bought a Gimson Robotics linear actuator. Impressed with it so far. Claimed at 29mm/s at 12V, they say it runs comfortably at 18V, which it has done under no load. I will have to run two circuits in the robot an 18V and a 6S ~22.4V circuit. I may have a third 5V circuit for led's etc.

To operate the the linear actuator, I saw in another thread the idea of using two microswitches (10A versions I located) and a servo motor to operate one or the other. I have some small servo's I got for ants, that I will use.

[Shooty]

Small recommendation on the microswitches idea: if you're going to do that, I'd recommend commissioning a 3D printed holder for those, as well as to insulate the connectors. I attempted to use the switches with my model, but just found them too fiddly in the end, and so used an ESC instead.

[Deathly Hallows]

Small recommendation on the microswitches idea: if you're going to do that, I'd recommend commissioning a 3D printed holder for those, as well as to insulate the connectors. I attempted to use the switches with my model, but just found them too fiddly in the end, and so used an ESC instead.

Thanks I will look at what I can do to fix them firmly.y

My biggest concern at this point is weight. When I weighed it last it was 11.5kg, without battery or any other electrics or the front ramp and hinge. This is a problem but not insurmountable.

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Chain drive is fitted, linear actuator is fitted. I installed a 12-24v led in rear for "alive/powered" indicator.

I will now continue to work on electronics. Before looking for ways to lose weight from the body.

Possibilities include:
Drilling holes in floor
Drilling holes in frames
Drilling holes in sides
Smaller battery
Lightening the wheels
Smaller battery

[Ocracoke]

Looking very neat and tidy, looking forwards to seeing this at Grantham if you are coming.

Possibilities include:
Drilling holes in floor
Drilling holes in frames
Drilling holes in sides
Smaller battery
Lightening the wheels
Smaller battery

I would probably go with "drilling holes in the floor", "drilling holes in the wheels" (which I added :P) and and "drilling holes in the frame" would help. I wouldn't fit a smaller battery right at this moment unless you could match the capacity with a lighter battery.

[Shooty]

I'd recommend holes in the base and rear myself. Mainly areas that don't leave important components in immediate danger. Also make sure holes aren't too near angles in the robot, as that increases the likelihood of splitting. My machine is fairly similarly built to yours, and when it came to the actual machine, I mainly put holes at the top of the lifter, any supports, the front of the base, and the rear where the Linac was (reasoning being the only machine that could go through the holes was one with a spike, and not with enough force to damage the linac). Do not recommend holes in the sides, they're far more likely to see action then your rear, and a hit to those could seriously damage the integrity of your bot.

[Deathly Hallows]

Thanks Shooty. - PS it was your thread where the linear control using micro switches was listed.

I have a bit of titanium plate behind rear bulkhead coring out some holes here would-be low risk
Once I know exactly where the internal electronics will be located I can drill the holes in the floor.
The aluminium square is 2mm so a few holes is not going to weaken it considerably

I am thinking of using polycarbonate with a thin Ti sheet on top for the bottom of the ramp. A composite structure you could say. It could take big whack and be lighter than steel I think. Anybody tried something similar?

[Ocracoke]

I did something similar with The Honey Badger 2.2 where there was a sheet of Aluminium over a layer of HDPE. Had I bolted it down properly, it would probably still be with me but it seemed to hold up quite nicely against non-spinners.

[Deathly Hallows]

I did something similar with The Honey Badger 2.2 where there was a sheet of Aluminium over a layer of HDPE. Had I bolted it down properly, it would probably still be with me but it seemed to hold up quite nicely against non-spinners.

Thanks may give this a go. Will have to think about best way to fix them.

[Deathly Hallows]

Having a bit of bother with the servo controlled linear - I took this from the Barróg thread

[QUOTE=RogueTwoRobots;468452]On point number 2, the easiest way would just be to use a servo to turn on a couple of microswitches, one for each direction. It allows you to control forward and back from one radio channel and the stock actuator motor will have a low enough current draw to not require any additional relays etc. Here's a setup in its simplest form; I usually tend to just hot glue the switches onto the sides of the servo and wrap a cable tie around them, but you may prefer a more robust/maintainable/aesthetically pleasing alternative

DSC_2215.jpg[/QUOTE

I assume I wired it wrong. But not sure how I identify the right terminals.

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My expectation was without either microswitch engaged it would be off. With one or the other polarity would be reversed.
I possibly toasted them in the process of getting it wrong.

The switch is a Z-15GW-B

The pin nearest the rocker is 1 - COM
Centre is 3 - NO
Nearest switch extended arm 2 - NC

Advice appreciated as my electrical know how is poor at best.

[PaulusSmallus]

I think if you connect on each switch:
pin 1 (COM) to the motor
pin 3 (NO) to batt+
pin2 (NC) to batt-

I don't think you will have blown them up as long as you keep the motor connected across the 2 common pins, you should be ok.

Let me know if this works, or if you want me to draw a circuit diagram.

Paul

[Deathly Hallows]

you're a genius! that works thanks very much