▼This page was part of an MTU course MSE4777 OA and MSE4777 OB/MSE5777/EE4777/EE5777: Open-source 3-D printing

Please leave comments using the talk page. The course runs in the Fall semester. It is not open edit.

A clamp is used in many stages of manufacturing and assembly. Holding things in place during these processes will yield higher quality parts and enable more complicated pieces to be built. By using a geared system, much more force can be placed on objects compared to an un-geared clamp. Cost efficient and expandable geared clamps will help enable growth in technologically deficient countries.

Bill of Materials

The clamping system is made up of the rack, and clamps. You will need two of the clamp assemblies for it to be useful.

1. Clamp Assembly
   1. 1X Base ~26 grams PLA or ABS
   2. 1X Cover ~36 grams PLA or ABS
   3. 1X Handle Gear ~17 grams PLA or ABS
   4. 1X Pin Gear ~2 grams PLA or ABS
   5. 3X Reduction Gear ~2 grams PLA or ABS
   6. 1X Spacer Gear ~1 gram PLA or ABS
   7. 1X 20mm M6 ~ $0.53
   8. 1X 30mm M6 ~ $0.65
   9. 1X 40mm M6 ~ $0.70
2. Rack Assembly
   1. nX Rack ~22 grams PLA or ABS

Clamp STL

Rack STL

Freecad Source

1. Source is available at http://www.thingiverse.com/thing:1183306

Tools needed

1. MOST Delta RepRap or similar RepRap 3-D printer
2. X-acto Knife
3. Drill with 6 mm drill bit (may not be neccesary for extremely well calibrated printers)
4. Pliers are also helpful

Skills and knowledge needed

• Know how to plasti-form with a bolt. (Screw into undersized hole to imprint threads).

Technical Specifications and Assembly Instructions

Prototype parts were printed in PLA with the following settings on a MOST Delta:

1. Print Speed: 110 mm/s
2. Temperature: 210 C
3. Layer Height: 0.15 mm
4. Infill: 30%
5. Nozzle Dia: 0.5 mm

Assembly ~10 min (See pictures to the right)

1

Bolts in base.:

On the base, insert the bolts in the following order, starting at the farthest hole from center and working to center: 30 mm, 40 mm, 20 mm.

2

Pin gear placement.

Put the pin gear on the 20 mm bolt.

3

Spacer gear placement.

Put the spacer gear on the 40 mm bolt.

4

1st reduction gear placement.

Put a reduction gear on the 30 mm bolt so the small gears mesh with the spacer gear.

5

2nd reduction gear placement.

Put a reduction gear on the 40 mm bolt so the small gears mesh with the previous gear.

6

3rd reduction gear placement.

Put the last reduction gear on the 30 mm bolt so the small gears mesh with the previous gear.

7

Cover placement.

Place the cover on top so all the holes line up.

8

Tighten 20 and 30 mm bolts.

Use the pliers to tighten the 20 and 30 mm bolts until snug.

9

Handle gear placement.

Place the handle gear on the 40 mm bolt and twist to engage a couple threads on the bolt.

10

Handle gear shift.

Push the handle gear so it meshes with the last reduction gear (this will push the bolt back out of the bottom).

11

Tighten handle gear.

Use the pliers to tighten the 40 mm bolt until snug, and then back a quarter turn.

12

Its Assembled.

Modifications

• 6 mm bolts are used as the shafts in this design, but there is nothing stopping use of other materials if the bolts can not be easily sourced. 3D printed shafts may work as well as wood dowels. The shafts could be fixed in place by melting the case plastic around the new shaft.
• The casing has a 10 mm hole that enables locking when the handle gear is aligned with it and a pin is inserted. Could be 3D printed, pencils work well too.

Cost savings

• If your solution is not a low cost one then it is not really appropriate.

At time of printing, 1kg of PLA cost ~ $23. At that rate, a system with 2 clamps and 1 rack would cost $4.55 in plastic and 3.76 in bolts. Total cost of $8.31.

This type of gearing is not common in commercial clamps, but clamps of similar size cost from $10~$20. Unlike commercial clamps, the range can be extended by printing more racks and chaining them together.

Cost savings $1.69~$11.69 or 17%~58%.

Area's for price reduction:

1. Use cheaper shaft material
2. Design static clamp end that requires no shafts, therefor only 1 geared clamp in necessary.

Current Issues

1. Chained racks will have a double tooth in the center, this prevents a clamp from crossing center. Find a way to remove half a tooth in freecad...