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$Id: BuildingLCQ.html 425 2014-05-18 15:57:10Z mrwhat $

Building laser cut Sleipnir Walin8r
Streamlined Quelab Configuration

I am currently working on updating for the latest configuration, E, generated circa 2/2014. These drawings will be in smaller groups, more convenient for cutting with human oversight at your own laser cutter. These drawings can be grouped into larger drawings for use with services like Ponoko in Inkscape.
File names have the file size, in MM, at the end of the file name. When importing SVG into Inkscape for conversion to DXF, resize the drawings to the indicated size.

Desc	Source file	Material Thickness	Contents	Notes
Wide Forks etc...	e20_30_116x174.pl	3.0mm	Forks with 3/16" diameter holes for standoffs and main axles. Also has motor gear, and motor mounts. All of these should be 3.0mm	Should split so that motor gear and mounts are separate drawings. It is critical that wide forks be very close to 3.0mm, but the width is less critical for ither parts. The motor gear must be a good bit less than the 4.5mm used for the main drive gear, so that it will fit within the side plates. 4.5mm seems a bit thicker than necessary for the motor mounts, but it is not critical that they be all that close to 3mm. The e20 should be removed from this file name, since these parts are not specific to the e20 configuration. So far, these parts are usable on all LC models.
crank links	e20crankLinks178x109.pl	1.5-2.3mm	links from spindle to legs	We need to fit two links within a 3/16" space. I am trying these in acetyl (Delrin), where 1.5mm may be adequate.
hips	e20hip45_180x132.pl	4.5mm	Linkage hip pieces, and a few space spacers, crank arm.	There is extra room on this drawing for small things.
feet	e20feet45_180x158.pl	4.5mm	Feet main gear spacers
BH EF	e20bhef135x252.pl	1.5-3mm	BH and EF links	Thickness not too critical for these
Main brace	e20mainBar45_144x191.pl	4.2-4.5mm	Main bar small braces	Main bar links, and braces. Also motor hub and some spacers. Thickness not all that critical for these parts. The braces might be a little more critical, as long as they are wide enough for main drive gear and some washers.
payload T/B/F/B	e20payload30_171x285.pl	3mm	Payload bay top, bottom, front and back	These are not very configuration dependant. We should remove the e20 from the file name, since they can be re-used over small changes in configuration
payload sides	e20payloadSides45_186x219.pl	4.2-4.5mm	Sides of payload bay	The only part of this which is really configuration dependant is the spacing of the axle holes
gear side plates	gearPlates103x113.svg	1.5-2.5mm	side plates for main drive gear	There are 7 in this drawing, although each robot only needs 4. I have found that even when thin, like 1.5mm, these do the job just fine. Note that I like to bevel the edge on the inside of these plates to help keep the motor gear centered on the drive gear, that these plates surround. I think it is a good idea to cement these plates to the drive gear.
D-forks	hipForks73x97.pl	1.5-3mm	Forks for top (D) node on hips	These hold the axle for connecting to the top cranklinks. Thickness is not critical
catch bar	catchBar107x53.pl	1.5-1.8mm	Bars to secure payload top	Must be cut from a more flexible material, like acetyl. These bars can be flexed in place, and do not need to be secured with screws.
catch tab	catchTab63x61.pl	1.5-2.2mm	Tabs to secure payload top	These tabs are screwed into payload lid to secur it.
shims	stackers61x61.pl	Various	standard spacers for wide forks	I often need these in 0.5-1mm PETG for enough space around the hip at D to have the forks hold a 3/16" long spacer. Unfortunately, my "4.5mm" stock is rarely wide enough for a 3/16" spacer. I usually make the wide-fork spacers using a 2.8mm spacer (common for "3mm" or 1/8 inch stock) and a 2.2mm spacer (common from 0.100 or 1.098 inch stock)
gear side plate	gearSidePlate38x38.pl	1.5-3mm	Single gear side plate	Convenient for cutting one side plate at a time from scrap Not necessary if you cut gearPlates103x113
motor mount	motorMount49x40.pl	3mm	Single motor mount pieces	Convenient for cutting one motor mount at a time from scrap Not necessary if you cut e20_30_116x174

• #10-32 die, to thread 3/16" OD axle rods
• Countersink, 82degree, at least 1/4" OD
• Syringe or bottle with squirt needle for Acrylic cement.
• Soldering iron, and solder

Expendible materials:

• Acrylic cement
  Weld-on #3 or #4, or Acetone.
  I hear Acetone works, but I have not built a robot with it. As far as I know, it takes longer to cure and may not be quite as strong as the Weld-on products, but strength is not an issue on this robot. The slower-to-cure quality may be an advantage since it may make it easier to construct the joints properly, with no air-bubbles, thus INCREASING joint strength.
• Metal-Plastic capable epoxy, such as JB-Weld
• Braided wire for motor leads

Hardware

2	3/16" OD hard steel rod, 12" in length
4 8 4	#10-32 nyloc nuts #10-32 nuts #10 lockwashers
8	1/2" long, 3/16" OD #4-40 round female-female standoffs
2	1/2" long, #4-40 threaded rods. May be constructed by cutting the head off of a #4-40 screw, and cleaning the threads.
4	#4-40 flat-head screws, 3/8" long
6	#4ish self-piloting plastic screws, 1/4" long
32	#4-40 screws, 1/2" long.	4 spindles 3*8 hinges 4 motor driver mount
12	#4-40 screws, 7/8" long.	4 motor mounts 8 hinges
4	#4-40 screws, 1 1/8" long. (main bar)
4	#4-40 screws, 1/4" long. (spindles)
8	#4-40 nuts Can use these while cementing parts	Main bar and motor mounts
36	#4-40 nyloc nuts	4*8 hinges 4 motor driver mount
16	#4 internal tooth lockwashers	4 motor mounts 4 main bar 8 spindles (both sides)
14	larger diameter #4 washers	2 motor gears 4*2 on spindles 4 under crank-arm
90	#4 washers	2*4*8 hinges 4 on spindles 8 motor mount 8 main bar 6 lid tabs
12	1/4" long, 3/16" ID nylon spacers	on B-axle to space out legs
8	1/2" long, 3/16" OD #4 nylon spacers	hinges
36	3/16" long, 3/16" OD #4 nylon spacers	3*8 hinges 8 hip-B fillers 4 motor driver mount
72	3/16" ID nylon washers (#10), around 1mm thick	~3*8 spindles ~16 B-axle 2*2*8 hinges

Main assembly parts:

• Laser cut parts, need 4.5mm, 3.0mm, and 2.2mm acrylic.
  The 2.2mm acrylic can be the 2mm from Ponoko or the 0.093 to 0.100" stock from several suppliers. Many suppliers deliver a sheet close to 2.2mm thick, even though the stated size indicates it should be 2.5mm thick. Be careful, Some suppliers deliver a 2.6mm thick stock for 0.100", which is too thick. In a pinch, 1.5-1.6mm stock can be used (usually around half the thickness of the 3mm stock)
• LM298 based motor driver module
• (2) GA16 (or 16GA) sized gear-head motors for 3-12v.
  30-60 RPM preferred. 15-120RPM will work.
  These have a 15.5mm diameter round gearhead, with flattened motor back and D-shafts.
  My supplier was fasttech.com, but they are now out, and I am going to e-bay.

For Uno-based Bluetooth remote control electronics:

• Arduno Uno compatible MCU board
• Serial-bluetooth module
• Female header for bluetooth module (usually 4 pins), and 6-pin female header for motor control board
• Make headers for UNO, at least 12. May want more to fill all sections of the Uno headers.
• Connection wire
• 3-AA battery holder (with switch, if possible)
• 3 14500 3.7v LiIon rechargable batteries (AA sized)
• LiIon battery charger
• Bluetooth Remote Control app for Android (3.0+?)
• (4) more each of 1/2" screws, 3/16" long #4 spacer, #4-40 nyloc to mount Uno.

General note on glues for Acrylic:

Do NOT use CA cement on or near acrylic. The fumes will mar and glaze the surface. Welding agents work wonderfully when bonding acrylic to acrylic. I am told that acetone will work, but it is slow, and may not make as strong a weld as the Weld-On chemicals. The weld strength is not likely to be an issue for this assembly, which does not experience any severe stresses. I have been using Weld-On #3 which is very fast. I am told that Weld-On #4 will be a bit slower and make a stronger weld. I am finding #3 too fast, and rather hard to work with, so I will recommend getting #4 if you can.

Welding is unnecessary for most of this project, simply an asthetic decision. However, welding the main drive gear to it's guidance plates should make the gear teeth a little stronger, which might be a good idea.

It may not be necessary to epoxy the motor gear to the shaft, but it should certainly make that connection stronger, and perhaps longer-lived.

Chassis assembly

These are still being re-written from the previous build configuration. This text should be augmented with illustrated, detailed step instruction pages as they become available

1. Cement main axle and gear
   Roughen gear near axle hole, and ends of axle standoffs.
   Center threaded rod on gear, dab a little cement, install standoffs to form an axle.
   clean excess epoxy, if any.
   set aside to cure
2. Cement motor gear to motor axle
   Roughen one side of a wider washer, and slip over motor axle, rough side out.
   Roughen one side of motor gear near axle hole, and one side of a motor gear hub piece.
   Place the gear, then hub on motor axle, with smooth sides facing each other
   Cement gear to hub while installed on axle.
   Drive the motor to make sure that gear is mounted perpendicular, and does not wobble as it turns.
   Allow cement to cure for a few minutes.
   Put some epoxy on top of the washer and at the edge of the gear hub
   Adhere the washer to the gear with epoxy, and the tip of the bub to the axle with epoxy.
   Drive the motor and check alignment
   allow to cure
3. Counter-sink one side of one hole on crankarms
   Counter sink should not quite make head of screw flush with the crank. The screw head can and should stick out a little (deeper may make the crank arm too weak). The counter sink only needs to be deep enough to increase the contact area with the flat screw head a bit larger to adhere to epoxy later. The head only needs to be recessed a little bit in order to clear the crank-links on the spindle.
   Roughen the walls of the countersink a bit, and roughen the underside of the screw head with a file. They will be epoxied to the axle later in the assembly process.
4. (Cut and) thread ends of axle rods
   If you do not want the axle tips to extend beyond the leg braces, you may wish to cut the axle rods. I do not (yet) know the exact desired length of the axle rods, so if you wish to cut them, you may want to assemble the robot with only one side threaded, measure the length, then remove, cut, and thread the other end when the desired lengths are known. I usually replace the axle with a shish-kabob skewer while working on the axle. this makes removing and replaceing the axle very easy.
   I have been putting a #10-32 thread about 0.5-0.8" long on each end of the axle.
5. Bevel main gear side plates (optional)
   A bevel on the inside of the drive gear side plates may help keep the larger diameter motor gear centered on the drive gear.
   To bevel these gears, I screw them onto a standoff, then put them in an electric drill. I then take the electric drill to a sander and simultaneously turn the plate with the drill and touch it to the sander to make an even circular bevel.
   The bevel should not quite go the full thickness of the plate, and be at an angle not more than about 60 degrees, making the thickness of the bevel no more than about 3mm (0.15")
6. Cement main gear side plates to main gear (optional)
   The teeth of the main gear might be strengthened by cementing them to the side plates. If you wish to do this, slide the side-plates on the axle, bevel side in (if beveled), and cement them in place.
7. Cement forks to Hip and Foot pieces
   Place about 5mm worth of stackers on the hip or foot piece under one of the wider fork pieces. If your 4.5mm stock is near 4.5mm, it will be sufficient. If this stock runs a little thin, try stacking one 2.2(2.5)mm stacker with one 3mm stacker. Align the fork and stackers with a 7/8" to 1" screw and nut, loosely. Apply the solvent to the edges so that it will capilary between the pieces, then snug (do NOT tighten) the screws until the cement adheres.
   Do NOT tighten, it will not strengthen the bond, and may crack the acrylic.
   Allow the cement to cure.

   Note that there will be 4 left-handed, and 4 right-handed hip and foot pieces.
   When the forks are installed "on top" of the foot/hip piece, half should face one direction, and the other half should face the other direction.

   After the wide forks have been installed, install the narrow hip forks in a similar fashion. The hip-D attachment will have two forks tynes, instead of one fork tyne on top of stackers. If your 4.5mm stock is actually thinner than 4.4mm, you may want to cement a thin PETG shim under one of the fork tynes. I recommend installing the shim UNDER each left-hand hip, and ON TOP of each right-hand hip. (Which one is "left" and "right" is not critical, just that you maintain symetry)

8. Assemble legs
   This one really needs its own page. The Leg sub-assemblies process is the similar to the one for the bolted assemblies just ignore the bolts on the forks in the photos. Cementing these forks is stronger, lighter, cheaper, faster, and more reliable.

   We are now using a screw with a nylon spacer, 2 flat washers, and a nylock for each hinge instead of a standoff, two screws, two flat washers and two lock washers.
   I am no longer recommending the additional braces on EF or BH. (Unnecessary weight and complexity)

   Nylon spacer hinges should have snug, but not tight nyloc nuts. I usually tighten them until I feel some resistance, then back off 1/4 turn.

9. Assemble main bar with drivetrain
   Cement the crescent from under the motor mount to the crescent shaped motor brace with screw-holes.
   Install a flat washer under the head of a 7/8" screw, and place this screw through one side of the motor fork.
   Then install the cemented crescent brace onto this screw, followed by two spacers, then the oval-shaped motor brace piece. Secure with a washer, lock-washer, and nut, loosely.

   Install 3 braces on each side of the main bar with 1 1/8" screws with a flat washer below the head.
   Then install the main gear axle onto the motor-mount side of the main bar, on the same side as these braces (opposite side of motor clip).
   Install the other side of the main bar onto these screws, and secure loosely with a washer, lockwasher, and nut.

   Slide the motor and gear assembly into place from the bottom.
   Place the crescent motor brace and back clip around the motor holding it into place.
   Rotate the motor gear until the hole is over the un-secured side of the motor fork. Install the other screw and washer by passing them through this hole. Plase 2 more spacers behind the crescent motor brace, then secure the back side of the motor clip onto the screw with a washer, lockwasher, and nut.
   A screwdriver may be used to brace this screw as the nut is tightened.
   Move the hole to lay over the other screw, brace it, and tighten the other nut.

   Make sure the brace holes are alighed to cover the axle hole, and tighten these screws.

10. Epoxy crank arm to drive gear axle
    Place an internal tooth lock-washer and then a flat washer on a 1/2" screw. Insert this screw through the non-countersunk hole, with the head on the opposite side as the countersink.
    Put a wide flat-washer on the other side of this screw, secured with a round standoff. Tighten the screw enough to engage the lock-washer securing the standoff in place.
    You may want to locktite this screw, since it can be hard to get to after the crankarms have been cemented in place.

    Roughen the crank-arm inside the counter sink, and near the hole on the other side. Apply some epoxy (JB-Weld) and screw this crank-arm to the main gear axle snugly.

    Repeat for the other side, making sure that the crank arms are exactly opposing each other (180 degrees apart), and allow to set.

11. Integrate payload bay
12. Mount cranklinks onto spindles
13. Mount main drive and leg assemblies to axles
14. Complete axle assemblies with brace
15. test
16. Install payload lid

Save the following LINKS to get production drawings:
The production drawings will not render in your browser. The lines are too thin.

This scale in the filename is for a rectangle containing the outside tips of the corner fiducials. This should make it easier to import the drawings, just set the scale of the imported object to the size referenced in the file name.
The spacing from center to center of the fiducials is actually 1mm less than the numbers in the file name.

1. Drive and main bar assembly
2. Leg sub-assemblies
3. Payload assembly
4. Main chassis integration

Last modified: 140518