We've had a pretty productive week so far! We're making good progress on two of the beetles, have one 'bot done, and are really waiting for parts to show up to get cracking on the others we're planning on taking to Motorama 2012. While we wait for those parts we have some pieces we can make ourselves, and we still have the wiring to do on Unlettered Understrapper 2.5. Hit Back after viewing an image.

We set Milly off and running on the remaining aluminium parts for the featherweight. While that was going on we decided to finish the lifter for the beetle. We've drilled and tapped one hole for the crank, to fit a #6-32 1" screw which will be Loctite'd in after assembly.

Looks like Milly has finished - we have the three aluminium wall pieces and a spare for each. Still some drilling and tapping to do, once the top and base plates show up.

With the aluminium done, we set Milly off on the UHMW wall pieces, and went to go find something else to do.

Here we've bolted in the crank for the beetle lifter. We still need to round off the ends on the sander, but it's looking okay so far.

A bit more drilling and tapping and the rocker arm has gone in place. Again we need the edges rounding down, but it's coming together nicely.

For fun, we decided to put the arm into place in the 'bot, using hex keys, and the holes all line up, so yay! :-)

Here's where the arm extends to, give or take, and it ought to be enough to be able to fall to one side and roll on to the wheels again. The only issue is that cranking the arm takes a bit of force, and we're not entirely sure whether the HD servo we have is up to the task. We'll have to see when the 'bot is a bit more assembled. We can always switch to a gearmotor, and figure out limit switches using a Team Delta relay.

Yay! The UPS guy just dropped off a fairly large box - let's see what's inside!
:-)

Parts for Formidable Fustigator 2.0: base plate; top plate; and boom strengtheners.

Parts for Poor Punctuation 2.0: top and bottom plates for a one-weapon-motor configuration; top and bottom plates for a two-weapon-motor configuration; a pair of UHMW rings; and titanium weapon ring and gears.

Parts for Malicious Mule: top and bottom plates; inner walls; spare outer walls; front and back plates; and aluminium outer walls.

Parts for Didactic Duelist 1.5: base plate; top plate; side walls; wheels walls; engine mounts; rear walls; and side walls.

We couldn't resist: we had to do a little on the antweight parts! Here we've drilled the UHMW rings slightly to accomodate #4-40 locknuts.

And with minimal effort the locknuts have been pressed into place. We had originally envisioned regular hex nuts, but inexplicably we don't have any, hence the locknuts.

Here's how the antweight parts stack together - polycarb, UHMW ring, titanium weapon ring, UHMW, and then polycarb. There will be a bunch of spacers holding everything together.

Meanwhile, Milly is still turning away on the UHMW parts. Because even half-inch thick UHMW is a bit bendy, we're only doing four inches at a time - the width in the vise, to ensure that at least that much doesn't flex while we're cutting.

Here's the front wall for the 30lb'er, and it's 26.5" long, so we're having to work around the lathe chuck to be able to get the middle of the part, but we finagled it successfully.

Here's a test-fit of the 30lb'er walls on the baseplate. If you look at the back wall, it's not sitting on the baseplate, so obviously we messed something up. On closer inspection we mis-measured the length of the side aluminium walls - they should be a quarter-inch shorter! Thankfully that'll be pretty easy to take care of tomorrow, so we've put it on the list of things Milly has to do tomorrow.

A quick trip to the mailbox yielded junkmail and a package from Hong Kong - more spiral bevel gears! We were planning on using these on the 30lb Sportsman Walker Cyber Scorpion 0.9, but we've scrapped that idea - just too complex with not enough time for Motorama 2012, but on the plus side it'll be a project that will keep us engaged in 'bot-building through the year, rather than just the few months leading up to Motorama 2013 ...

Here we've already counter-sunk all the holes for the top and bottom plates for the antweight's two-motor configuration, so we're about to throw some team colour on them, while we fiddle with some other parts ...

... Namely the antweight weapon motors. They came with set screws in place for prop-savers, but by golly they were in there tight! We ended up Dremelling them off.

Right - we've taken the can off one of the motors intending to press the titanium ring onto the can!

Er - yeah ... not so much. We've mangled the can pressing the gear on, so something's obviously not right here. We broke out the calipers, and groaned. For a press fit you typically aim for three or four thousandths difference in size. What we have here is four hundredths difference. Grr. Our bad on the DXFs we sent to the Whyachis, so what can we do about it?

We set the Dremel-a-like onto it and see if we can neatly take the inner diameter of the gear to somewhere close to the motor outer diameter. Unfortunately we got far too carried away - not realizing the Dremel-a-like worked so quickly on Grade 5 Titanium, and now the ring just slips down the motor. Drat!

At this point we have one good motor, one bad gear, and two fresh gears. Obviously we're going to have to order some more motors, but we started wondering whether we could reclaim the bad gear some way, so we built a jig ...

... And applied some Loctite to the motor/ring combo. Ordinarily we'd have used duct tape, but felt this operation needed a little more finesse. The jig has the ring 0.25" from the bottom of the motor, so if this works we have one working weapon motor. We'll find out in the morning whether we were able to save the titanium gear.

But the first thing we have to do tomorrow is clean, tidy, and organize the garage Build Space, because we wasted a whole heap of time today simply trying to find things! This place is a bomb site hit by a tornado! So that's the plan for first thing tomorrow. For now, we're going to have a gin and tonic, and order some motors ...

This is turning into quite a productive week! Having made a solid start on Versatile Villain 0.9 we decided to gather up all the milling we need to do and take care of as much of it as possible. And we heard from the Whyachis that our parts will actually be here Thursday rather than Friday, so that should make Friday a busy day too! Hit Back after viewing an image.

The first order of business is the table saw, though. We need to cut some walls and chassis blocks from our recent McMaster order. We have some 0.75" UHMW chassis blocks for Macchiavelian Malcontent 0.9 and some pieces for its 4-bar lifter. We also cut the UHMW and 6061 walls for the next version of our featherweight.

Speaking of the featherweight, here are the two weapon motors - we need to make mounts for them, and so cut out a couple of pieces of 1/2" polycarbonate. Here you can see we're missing a pinion gear, but it's on order from China.

The next job for the table saw is bevelling the walls for Formidable Fustigator 2.0 which didn't take too long, but it was quite daunting pushing a three-inch piece of aluminium across the blade and pressing it into the guide to try and keep it level (our table saw has a dip next to the blade) - definitely had to rest the fingers after that job, but they're all intact!

Here's a completed motor mount - fairly quick and easy to whip up, and we were actually quite accurate in our drilling, which made a pleasant change ...

And here's the second. We haven't figured out eactly how far the mounting distances are for these spiral bevel gears, but we'll sort that out once we have the pinions on the motors and a shaft for the main gear.

Well now ... what have we here? These are the two DeWalt motors that survived from the first version of the featherweight, and they don't look like the spare we have. We Googled for information about high and low speed, and found Team DaVinci's handy page which informed us that these DeWalts were in low gear - doh! We set about disassembling them and removing the locking ring to get them into high gear. It took a while, because those planetary gearboxes are fiddly, but eventually we got the hang of putting them back together layer by layer.

Speaking of things surviving from the first version - here are some pieces that didn't! We decided to spend a little bit of time going through the parts to see if we could use anything as spares.

One of the motors was good, and we were able to scavenge sufficient gears to build a gearbox for it, so these are all the DeWalt spares we have now - three motor/gearbox/mount combos. [Actually, we have two more, but Scott's going to buy those for his featherweight - Ed]

While we were scavenging we fired up Milly, with a program to cut down the lifter arm for the beetle. We've figured out by trial and error that if we run the spindle at 1500rpm, set a feed rate of 6 inches/minute, and take 1/16"-deep passes we get good results. Sure, it takes a while, but when we can give it to the CNC PC to take care of, the speed doesn't matter too much.

After a while, this is what we ended up with for phase one. Looks pretty good!

Next we set up a program for the holes for the arms. Truthfully, we do have smaller endmills, but it's a hassle to switch them, so we're quite content to keep trucking with the half-inch one.

Et voila! Phase two is complete - just ignore that errant cut on the right - operator error :-O We moved the part along in the vise and moved on to phase three, and pretty soon had a finished part, which we put aside and moved on to the mating part ...

... The Plow. Truthfully we should have trimmed this on the table saw earlier, but we forgot. It took a while to cut the 2" angle leg down to 1.375", but hey: CNC PC!

While Milly was doing her thing we checked out the lifter arm - just like the CAD! :-) We only need to drill a couple of holes in it and it's a finished part.

Meanwhile, upping the weight class to 1000% we decided to do a test layout of the featherweight. The only parts we're missing for the body are the batteries, motor shaft and pulley - oh: and the top and bottom plates, but it's already starting to come together.

After Milly was done creating aluminium sprinkles we checked out her work - the plow has a small pocket to mate with the arm. There was probably a better way of creating it, but for the life of us, we couldn't figure out how to make a rectangular pocket with round endmills. Maybe we should read a couple more books ...

The next (repetative) task on Milly's plate is to cut lips in all the aluminium walls for the 30lb'er. Again, taking 1/16" passes it takes a while but the results are fine, and we went back to the beetle.

A little bit of drilling-and-tapping later and the plow is mounted on the lifter arm. We're still debating whether to countersink those holes for flat-head bolts, but for now we'll stick with buttonheads.

The last shot of the night, with the aluminium wall parts all cut for the top and bottom plates. Tomorrow: cutting lips into the UHMW walls - hopefully just in time for the plates to arrive!

We received an email today from the Whyachi folks: our parts should be here Friday! In the meanwhile, we have a few 'bots to work on, including our newest beetle, Versatile Villain 0.9, which we made a start on yesterday. Let's see how far we can get today! Hit Back after viewing an image.

Here's our starting point for today: the bottom of the chassis for the beetle. Yesterday we noted that the original chunk of UHMW was a quarter-inch too thick, and we'd have to trim it down, so here we go ...

We're almost getting the hang of clamping parts and not using the vise. It means stopping now and them to adjust the clamps, but that's much better than milling through the bottom of the 'bot!

Et voila! Actually, not quite. Things didn't look quite right, and so we took some measurements. Somehow we'd only shaved off 0.15", not 0.25" - doh! So we were going to have to run the G-code scripts again.

The inner portion is done, and Milly managed to shave a three-foot long streamer during the process - nifty! Now to adjust the clamps for the outer portions.

And we're done! For sure, this time :-) This picture was taken after using a box-knife blade (carefully) to strip off all the hairy bits. Came out nice, we think.

There is still the issue of the lip being too shallow in the corners, so back on the mill for a bit more to cut the lip a bit deeper.

And there it is: the top plates fit, and the chassis block is done - yay! Not bad for two day's work ... we were actually doing other things while Milly was running, but just organizational stuff. Honest.

Here we've drilled the pin-holes for the rocker and the crank arms for the 4-bar lifting mechanism. Thankfully we had spares, as we'd managed to snap a 1/16" drill bit in one of them, but no worries.

Just a quick test layout with pin-holes drilled in the internal polycarbonate walls. Looks about right to us.

On the other hand, this doesn't look right: the PWM cable for one of the inputs on the RobotLogic Mecanum Mixer seems to be reversed. Rather than send it back, or fiddle with the soldering iron, we're just going to make a note to plug that connector into the receiver backwards.

After a bit of drilling and tapping we have the inner walls installed, and things still seem to fit okay, except we've just realized that we're probably not going to be able to actuate the crank in the position it's currently in.

Here are some of the internals of the 'bot, including the omniwheels and mounts, mixer and receiver, servo for the arm, and battery and power switch. Still needing to be ordered are the four FingerTech TinyESCs and four Pololu 50:1 HP motors.

We haven't done any milling on the arm pieces yet, but decided to do a test-fit anyhow, and things look about right so far. Weight-wise we're also doing good - a little over two pounds without the motors or speed controllers.

Last shot of the day as we wrap up - the top plates are installed and the 'bot looks pretty neat :-) Still plenty of milling, drilling, tapping, and assembly to go, but for now - as the temperature dips below 40°F it's time for dinner!

Okay - after a fun Christmas Day (love my Kindle!) it was time to get serious about Motorama 2012. We have the week off this week, so looking forward to a getting a whole bunch of building done. As we're waiting for parts for the new 'bots, and didn't much fancy tackling the wiring on Unlettered Understrapper 2.5, we decided instead to spend some time working on the chassis for our other new beetleweight Versatile Villain 0.9. Hit Back after viewing an image.

Our mill vise can't handle the 8.75" chassis block, and given our problems working on the fairyweight chassis with it in the vise, we decided instead to try bolting it down to the cross-slide.

We elected to tackle the milling in three segments - middle, front, and back - with the front being to the right in the picture. There were a couple of spots where we weren't entirely sure about clearances of the bolts for the clamps, but we figured we'd give it a shot anyhow!

A quick shot of the CNC control system - Mach3 - running our G-code. There are a number of functions we still haven't figured out yet, but we appreciate the opportunity to practice. It was actually a bit daunting going straight for a one-off block we don't have spares for should something go wrong, but there's no time like the present!

Oops! We hadn't entirely positioned the block properly, because we hit the extend of the Y-axis. So we stopped the G-code program and repositioned the block. We were aligning the block with the edge of the cross-slide, which allowed us to keep 0 on the x-axis in the same place, and just had to recalibrate the Y-axis.

And we're off and running! We're going in three passes - 0.375", 0.75", and 1.125" deep. It's only UHMW and we could probably do more at a time, but we wanted to be a little careful.

Having completed the first pass in the middle section, we took a quick photo and reset for the next round.

Cool! The middle section is done, so it's time to adjust the clamps, and load up the G-code for the front third.

We've reset the clamps, and we're about to get the next section underway. We did take a sanity check to ensure that the spindle will keep clear of the clamps, and it does, barely - but "barely" is enough :-)

After some more 220V consumption we have two-thirds of the milling done. Time to readjust the clamps again for the final third.

Here's a gratuitous shot of the last section underway. You don't have to click on this one ;-)

And hey presto! We're done! Actually, we're not done because the original material was actually 1.5" thick and the 'bot is only 1.25" tall, so we'll need to load back up tomorrow and take the base down a bit. You'll also notice that the top plates don't quite actually fit, as we were a little off in calculating the curves, so we'll have to touch them up a bit too.

We also milled slots for the weapon arm in the front and back walls. We'll need to run a razor blade over the base to clean up the 'hairy UHMW' from cutting in the 'wrong' direction. CNC'd material always end up looking nifty.

Today was officially a Snow Day, with Austin having received a couple of inches of snow overnight - not a common occurrence as you may imagine. Amidst the chaos and devastation [Rolls eyes - Ed] we snuck out and went back to see Chris at Speedster Hobbies to do a little more sawing, and to use his very nice lathe. Granted, Milly is part mill-part lathe, but right now she's set up for milling, and so it was just easier to do the things we needed to do over at Chris's place. Thanks again Chris! Click Back after viewing an image.

First on the bandsaw were the DeWalt keyed shafts for Formidable Fustigator 0.9 to trim them down to size, which hardly took any time at all. You'll note that the bottom shaft is different from the rest - it's not an official Team Delta shaft - it was one we cooked up many years ago, but works fine.

We also re-ran the aluminium tube parts for the featherweight - we had forgotten until we laid the parts out the other night that the lengths of tube were oversized, so it was a pretty quick and painless operation to trim an eighth off each piece. Not shown here are the twelve pieces of 5/16" aluminium round we cut for axles for the two beetleweights.

Moving over to the lathe and we had a couple of things to accomplish. Firstly trimming and boring the beetle axles, which was faily quick and easy, and we're sparing you the photo. Second we needed to cut a well in the two blade caps for the delrin bearings, which is what we're up to here.

Ta-daa. The 3/16" delrin protrudes the required 1/16", and all is well. On to the second one.

One of these days we'll learn that material measurements aren't exact. For example, the nominally 3/16" (0.1875") delrin was actually 0.22" inches thick, so we had to go a little deeper on the wells to make the stack of two blade caps and two delrin washers 1.25" tall, but eventually we did. With profuse thanks to Chris we headed back to the Build Space.

This antweight will be the death of us. In reassembling the chassis we managed to snap off the power leads to one of the drive motors, and had a devil of a job reattaching them. As you can see we made a mess of the back of the tiny Pololu motor trying to attach new leads, and finally called it a night. The weather forecast for tomorrow calls for a high of 56°F, so we're going to bed early and will be taking full advantage of the balmy temperatures and maybe - just maybe - finishing a 'bot!

We have a number of parts that we needed to chop up for a few 'bots, and we were beginning to fret about how well we would do at that with the jigsaw when our Knight in Shining Armour got in touch. Chris from Speedster Hobbies let us know we were welcome to come use the bandsaw again, so we loaded up the Botmobile, took a telecom lunch, and headed up the road. Click Back after viewing an image.

Chris gave us a refresher on the controls of the bandsaw, and with a solemn vow not to sacrifice any digits to the machine we were left to get on. We decided to start easy, and cut a length of the UHMW pipe we're using for Nihilistic Naysayer 2.0's drum.

Seeing as though that went so well, we decided to skip to the other end of the material spectrum and trim the tool steel teeth to the same length as the drum. With the blade feed slowed to the slowest setting, and all the country-style gravy coolant washing over the part - plus the frigid air - the piece didn't even get warm!

A bit more sawing later and we had some plastic parts to clean up: the drum in the background, and some 1" rounds of UHMW for gearboxes for the twelve-pounder.

Here are some short and sweet pieces. In the forground the retainers for the weapon shaft on the thirty-pounder Formidable Fustigator 0.9, and in the background two different types of main weapon shaft. The left is keyed stock, which would need to be bored out for the retainer, and on the right some tube which would need a keyway milled into it. We weren't sure which direction would be the easiest, so we cut parts for both.

Here are the teeth we chopped down earlier. Those bars are quite hefty!

And plenty of aluminium pieces for the featherweight too! Top-left we have a piece of 6" pipe cut into quarters for the rear curving wall. Top-right are the rings that the blade sits on (which need to be lathed for their delrin inserts). Front and Center are the wheel guards for the ends of the legs.

Finally some aluminium pieces for our beetleweight Versatile Villain 0.9. Top-left are a couple of pieces of angle for the plow. Top-right we have a couple of rocker arms for the four-bar mechanism. Bottom-left are a couple of the arms themselves. Bottom-right are a couple of cranks for the four-bar.

All right - time to get back to work! Thanks a million Chris, for all your support!

Direct from the frozen tundra of Dorchester, Wisconsin, comes a box full of win: Whyachi-Waterjetted Parts! There are a few parts yet to come, because - get this - they're being heat treated! Oh yes! But as you can see below we have plenty to be getting on with ... Click Back after viewing an image.

These diminutive pieces are top plates for our 150 gram fairyweight. We could have done them ourselves, but with the small size of the parts and relatively large thickness of our fingers, it was just easier to add them to the batch.

Next we have the chassis and drive walls for one of our three pound beetleweights. The black block is UHMW, with some 6061 top plates, and polycabonate motor and wheel mounts.

Here are the frame parts for our other beetleweight - rear wall (with spare), outer walls (with spares), inner wall, drive and weapon motor mounts, and wheel mounts, along with top and bottom plates.

Stepping up a weight class to the twelve pound hobbyweights, and here's the chassis for the second version of our drumbot. 3/8" 6061 outer walls, and 1/2" polycarbonate internals. We're looking forward to putting this one together, because it should be fairly quick - after all, we're really just putting a new frame around the old internals.

Finally a few parts for our thirty pound featherweight. Above are the two weapon braces from 6061 aluminium, and below are some nylon bearings for the weapon blade. Unforutnately the weapon blade hasn't made it here yet, because it's being heat treated, but should show up next week, along with the top and base plates.

Thanks to Jake at Team Whyachi for the immaculate cutting job!

With our geometry lesson from yesterday we were finally able to sit down and finish the design for our second Motorama beetleweight: Versatile Villain 0.9. It wasn't without issues, though, and we actually ended up starting over, after realizing that the initial design we'd spent a lot of time on would wind up about three-quarters of a pound overweight if we carried on the way we were going. In a three pound weight class, that's not going to fly! So we started over, with a little copying and pasting of parts, and came up with this design, that we hope will work well. It should weigh in around 2.9 pounds, when all is said and done, so here we go!

Starting out with the chassis, and we have a chunk of black UHMW - although rendered here in white to make it easier to see what's going on. We're going to start by having the outer shape and wheel holes cut, then clamp it down onto the mill and go to town hogging out the inside. There's a lip for the top plates, and when all is done, we should have an 8.75" x 8.75" x 1.25" unichassis weighing just over half a pound.

Into it we will mount a few polycarbonate pieces, wheel/motor mounts, and two inner walls to help keep the lifting arm mounted properly.

The top plates are 1/16" 7075 aluminium, which will be cut to fit either side, and make for easier replacements. There will be a couple of threaded spaces inside to help keep the pieces from buckling near the center should we end up with another 'bot on top of us.

Here's the drive train - very simple. We originally wanted to use everyone's favourite 1000rpm 12V Hobby Motor imports, but four of them wound up being way too much weight to be able to work around, so we're going to switch to Pololu 50:1 HP motors. At 11.1 volts on 1.5" wheels, we ought to be able to get around sufficiently quickly to make use of the weapon.

Speaking of which, here's the mechanical bit of it - the rocker and crank, mounted to the inner polycarbonate walls. The pieces themselves are 1/2" x 1/4" 7075 aluminium with steel pins for links. The weapon actuator is (currently) a 1000rpm Hobby Motor, but given the space and weight we have to work with, we may be able to trade up and simplify the limit-switch/h-bridge design and just plunk in a heavy duty servo.

Adding in the lifting arm, which is 1" x 1/2" 7075 aluminium. It protudes a little from the front to more securely mount to ...

... The plow. We've debated stretching the plow out to the whole front of the 'bot, but again it wound up being too much weight, so we're going with the shorter, cuter, version.

The electronics are: drive speed controllers in red, battery in blue, receiver in orange, and a Robot Logic Mecanum Mixer in green. We're looking forward to trying this piece of equipment out - in the past we've had three omniwheels, and haven't needed a mixer, but with four, it's way easier to plug this in, than to try and figure out how to do a mix on the transmitter!

This 'bot will physically be the largest beetle we've ever made ... all our previous designs have tended to be extremely compact - we'll actually have room to move around inside this one.

And of course, it will compete in team colours.

Unfortunately we haven't quite finished all our design work, so we haven't been able to order everything we need in time for this three-day weekend, so we're going to have to amuse ourselves with some general building this weekend. We headed out to the build space to dig out some parts, and to figure out some design issues. Click Back after viewing an image.

One thing on our list is unearthing the DeWalts and omniwheels for Formidable Fustigator 0.9. We last had them installed in a middleweight we didn't get to finishing, which we dug out from behind all our materials, and unbolted the top plate from.

As you can see, there are four DeWalt/omni setups in the 'bot, so hey presto! We have a spare. We're still not 100% sure whether we want to use the DeWalts, or some Craftsman 19.2V drill motor/gearboxes - it'll come down to weight at the end of the build.

Next on our list of things to do is to design a new gearbox for Nihilistic Naysayer 2.0's Handiworks motors. Last time one exploded from a hit, and we want to make them a little tougher. We remembered back to making custom gearboxes for Anaphoric Antagonist 1.6 and it was a fairly simple operation. We took apart the damaged Handiworks from version one and took some measurements.

Part of the reason we haven't finished our design work is because we need to design lifting arms for our fairyweight and a beetle. Starting with the fairyweight Machiavellian Malcontent 0.9 we took some 1/4" balsa and a 1/16" drill bit, and started joining things up with rivets.

The first stab, and we realized that when in the 'down' position, the arm wouldn't be sitting flat on the top of the 'bot, which obviously isn't ideal.

Also, with the arm in the 'up' position it sits over the 'bot, rather than toward the front, or even in front, so we need to rethink this position.

After making the rocker (the shortest piece) a little longer, we used a piece of aluminium to represent the top and bottom of the body, and worked around it to ensure the arm laid flat in the 'down' position.

By moving the pivot points closer to the front of the 'bot for the longer upright, we were able to see more of a forward motion to the movement of the arm, which is what we're looking for.

To finally nail down the sizing and positioning, we cut the balsa to the actual size of the 'bot, and checked the geometry in the 'down' position ...

... And the 'up' position - you can see here that we have a much more forward final position, which is what we were shooting for!

Here we're playing with the micro-servo which will power the arm in the 'bot. It took a while to find both a working receiver and a working BEC to power it - must remember to order a new receiver! The little servo seems to have quite a bit of oomph, so it ought to do fine in powering the arm.

Second verse, same as the first. On to the arm for our second beetleweight for Motorama. We used the rough geometry from the first attempt to pin together the pieces here. With some extra wood representing the size of the body in the middle, the arm looks right in the 'down' position.

And looks pretty good in the 'up' position too. All in all we're happy with these designs, so we recorded the measurements of the pin holes, and went back to the CAD for the two 'bots to work on designing the arms.