LynxMotion T-Hex - 3DoF - starting from scratch... or not?

Lynxmotion Legged Robots
1

Well guys, I got my bot…

It looks quite good, until my rejuvenators-eye began noting things… heat shrink as servo-cable protectors, and even medical-class rubber tubing (often used for slingshots too) and then the board count doesn’t seem to match… ( then I looked again, and saw some items are plugged into others - DOH!)

Then examining the brushed-metal First-Series T-Hex chassis, I saw a lot of ragged edges around access holes, that could cut protectors and cables easily. I’m going to have to strip her to parts, and file all the chassis and leg parts to get rid of the sharp edges. Probably gonna hunt up some grommets too, just to be safe. Were all the brushed-Aluminum chassis that rough?

Then seriously thinking of ditching the Philips-head bolts/screws, and going with Allen-head ones. They don’t strip out as often. Do the new ones come with Allen-heads?

To save me the trouble, anyone want a brushed aluminum chassis for a matt-black one? Odd, there is one set of pieces that are black on this setup, the mid-leg straight-piece… another item to ask the seller.

Will update ya when I’m back to parts… and begin my cleanup.

WhiteWolf - T-Hex Bot-Beginner.

2

Guys:

Seriously considering replacing all the hardware on this T-Hex 3DoF chassis, and need to know how much Allen-head hardware will set me back. Anyone know offhand?

If not, I’ll make a list of it all when I have the beastie apart, and let y’all know (and which ones can be replaced by the plastic plug-rivets)

WhiteWolf,
off to dis-assemble his electro-pet!

3

Sorry, my T-Hex is more or less original parts (except electronics). Have not had many problems with things cutting or stripping very many screw heads. When worried about the looks of the wires or cutting, I will sometimes use some stuff to wrap the wires. What I currently have was recommended by Orion Robotics (Basic Micro), which I ordered a whole roll from McMaster-Carr.

1 9284K513 Choose-A-Color Expandable Mesh Sleeving, 3/8" ID, 3/16" to 1/2" Bundle Diameter, 50' Spool, Black 1 each in the morning 14.96 each 14.96
It was more important to me on the Orion Robotics, as their legs have really sharp parts that rotate within the body of the robot and they are using Lipo batteries, which scare the c… out of me.

4

The brackets are / were mass produced and should not have had very jagged edges.

No, although that is an interesting idea. We’ll see if that’s possible.

5

Coleman:

The critical ones are those blasted 2-56 bolts with the nuts that are used to attach the leg-brackets to each other and other pieces… I did a count as I went through the 3DoF assembly:

  • There are 68 (sixty eight) 2-56 x 0.25" screws (bolts aka ‘machine screws’) & 60 (sixty) 2-56 nuts. The mismatch is because of circular 0.25" standoffs use 4 each (used to space the front legs out)
  • There are 32 (thirty two) #2 x .250 self-tapping screws.
  • The 3mm x 8mm bolts used to secure the bearings don’t really need swap-over, but if they were, there are 18 of them in the 3DoF legs (assume 24 in the 4DoF)

I haven’t checked out the cost of replacement at a hardware supplier, like microfasteners.com or such… bit I will if anyone is interested.

WhiteWolf

  • stripped Philips heads drive me to drink! and curse! and use power tools!

PS: Damn that was easily researched:

prices sourced from www.MicroFasteners.com:
= 2-56 x .250 screws & nuts ( total ) 68 screws & 60 nuts

  • SBS0204 - 2-56 x 1/4 - Button Head Screw - Stainless 50 pcs/pkg = $5.80
  • HNSS0256 - 2-56 - Hex Nuts - Small Pattern (Thin) - Stainless 100 pcs/pkg = $3.40

= #2 x .250 self-tapping screw ( total ) 32

  • STP 0206B - #2 x 3/8 - Button Head Hex Drive Sheet Metal Screws 100 pcs/pkg = $5.20 (black oxide)
  • STP 0206 - #2 x 3/8 - Button Head Hex Drive Sheet Metal Screws 100 pcs/pkg = $5.20 (plated)
    ( they don’t carry a 1/4" size )

= 3mm x 8mm screw ( 1@ for bearing mounts ) = 18 + 18 x 3mm lockwashers

  • SBMS3008 - M3 x .5 x 8mm - Button Head Socket Screws - Metric - Stainless 20 pcs/pkg = $2.30

  • HNMS030 - M3 x .5mm - Hex Nuts - Metric - Stainless Steel 50 pcs/pkg = $2.20

  • LWTM3 - 3mm - Lockwashers - Internal Tooth - Plated 50 pcs/pkg = $1.50

  • LWM3 - 3mm - Lockwashers - Split - Metric - Plated 50 pcs/pkg = $1.05

I dinna bother to break down the price for the precise numbers… just sourced 'em to show how inexpensive the swap-over would be.

6

Not to start a new discussion within the same topic, but rest assured that we are taking a different approach with the SES V2 by drastically reducing the number of different hardware included in any V2 kit to a bare minimum.

7

Hmmm…Well, I’m going to see if any local hardware suppliers can sell me the 2-56 and 3mm hardware to replace the Philips-head stuff. I don’t see an urgent need to replace the #2 self-taps, as they only go into the plastic servo horns, and are not prone to stripping - besides, they don’t have #2 x 1/4" ones, only 3/8" (50% longer) Not going to get 'em locally even if they have 'em, as I’ll wait until I replace my servos (and get the free metal servo-horns)

For those of you who bought the bulk servos w/ metal horns, are they tapped? If so, for what thread? It might be worthwhile to tap the horns in the long run… yes? Opinions?

If I had to ‘go it alone’ (vs. placing a bulk order to make ‘hardware replacement kits’, if there was sufficient interest) the price for the 2-56 screws & nuts, and 3mm screws, nuts & lockwashers, from www.MicroFasteners.com , would run a bare $13.00 (that’s USD), plus any shipping costs. As its under $20 Cdn), Canadian Customs shouldn’t assess any duty. Up here, I’d see 13% tax (another $1.69 Cdn)

Note: I calculated for both the split-type lockwasher ($1.50/pkg.50), and the internal-tooth’d type ($1.05/pkg.50) and chose the maximum - it would be $0.45 less if one chose the split-type lockwashers (me, I’d prefer the internal-tooth’d lockers personally)

So, if I can get all my hardware up here for under $14.70. I guess I’ll do it myself. I’ve already gotten my black tye-wraps and 1/4" ‘split-loom’ type conduit (also in black) so I’ll be good to go on re-assembly.

Note: On that ‘jagged holes in the chassis’ issue, seems the holes furthest aft in the chassis plates were roughly reamed by a former owner/assembler, and not filed smooth. Once I saw it was just there, I handled it myself, but may look into grommets anyway, just to be safe and neat.

WhiteWolf, Ottawa.- who may need some ‘assistance’ upgrading his xBee modules, if he can DIY, that is…( but that’s a thread for another forum section, yes? )

8

Sigh :confused:

Well, it looks like the local hardware suppliers either have ridiculous prices, or they can’t get stock of the hardware for ~four~ weeks. :open_mouth:

So I’m probably going to place my order with MicroFasteners tomorrow. I realized I only need to replace the M3 & 2-56 bolts/screws, not the nuts & washers (its the Philips-heads that are the issue, right?) so this will cut down the renovation cost. My only delay is asking if he’ll sell me 1 & 1/2 packages of the 2-56’s so I get 75 instead of 100, saving $2.90 on the spare 25. (* But if someone else wants to renovate as well, I’ll buy 150 of 'em, and we can split 'em 75 each! *)

PS : Anyone have a spare pair of " RB-Lyn-240 " aka " AHS-02 Aluminum F/F Standoffs " ( 1 & 5/16" x 1/4" ) The T-Hex is ~supposed~ to have 12 standoff/spacers in the chassis, but my kit seems to lave ‘lost’ two somewhere along the line. I really don’t want to have to buy a whole 10-pack to get the missing pair - and the hardware suppliers don’t carry them! So if you have a spare pair, and would like to help a novice-roboticist out, let me know, hm? I’ll cover postage!

WhiteWolf, Ottawa

9

The metal servo horns are indeed tapped (2-56).