The technical support Q&A is updated as questions are asked, answered, and shared, so as to increase knowledge generation and sharing. If you would like to submit a question, contact
This email address is being protected from spam bots, you need Javascript enabled to view it
. Many thanks to the Legacy Foundation.
Press Construction: Bolts and Bars
Press Consturction: Pivot Placement
TMC vs Posho Mill and building locally
TMC Construction Tips
March 7, 2007: UGRF Press Construction - Bolts and Bars
In response to the first set of images sent by the UGRF foundation, logging their construction of the briquetting hand press, the Legacy Foundation responded with the following input:
"I expect that you had to weld bolts and bars together to
make up the full length bolts required. That's normal. Make sure the main opipes
for the main beam and handle are at least 1" dia better 1 and 1/4"
(ie 30 to 35 mm dia) and that you make the holes where shown in red, to avoid
splitting the wood.
The other changes are shown in red ink and blue ink.
[* Note on the image says: In the above "full-down" handle
position, the gap between the top and the bottom beam is to be about
one inch larger at the front of the press (right side) than at the rear
of the press (left side).]
The pistons can be made in two halves or even out of four
pieces as shown in the manual.
The adjustment is usually made in the shifting the pivot
hole (in this case down) in the rear legs. The changes form the
drawings come about because the lumber is almost always of a slightly
different dimension from place to place."
March 29, 2007: EEDI Press Construction - Placement of Pivots
The first steps of press production have resulted in a few questions concerning placement of the front pivot hole. See the first pictures from production in the photo gallery. The Legacy Foundation's response:The fundi is cautious about the last two holes and rightfully so.
1) The hole through the fat, square, press leg end of the handle has to be toward the top of the handle due to the load on it. If you put it at center it can split the handle at that point. Take a good look at the construction manual where we show the parts all laid out on the ground. The handle is upside down but the hole positions are shown there.
2) The handle end near the hole is rounded a lot on top, say 1" radius in the top corner. The rounding is a lot more gentle around the lower corner. Still it may stick into the press about 1" at full down or up position but this is not critical. and can be adjusted easily. Again the diagram in the construction manual will show the shape needed (again, caution, because the handle in the diagram is upside down).
March 23, 2007: EEDI TMC Planning - With and Without Electricity
For the EEDI project, five teams of entrepreneurs from five different wards are being trained. Only two of these wards have access to electricity, which is what the basic TMC machine is designed for. To address this challenge, the Legacy Foundation has also designed a more complicated machine that can run on bicycle or hand power:
The TMC is indeed new and complicated for most fundis but we are learning how to
make it simpler and less expensive as we move through the fabrication of it here
in Kampala. As I had mentioned early in our communications, if you have access
to electricity or a diesel driven posho mill (of the Hammer mill type) it might
be better option to pursue. We did not pursue this because we have understood
that because the participants will be returning to their villages they will be:
1) scattered 2) without electricity and 3) unlikely to have the skills to
manage such a mill.
That is why we proposed the more (initially) technically challenging,
thresher masher option for your project. In so doing, it increases the burden because we are starting
from scratch. But then again, developing capacity for local manufacture is our intention.
I can assure you that we can make it there in Lushoto with some of the
clever jua kali fundis who are bound to turn up there but it will
require extensive work with them to make it right with existing resources in their own working environment. Still, I would rather that we work it through from scratch with them on site, than revert to an
institution for the solution because the capacity and cash flow is most needed
in Lushoto.
May I therefore suggest that you first contract TDTC for only one machine
there and that we try to make one up with the local workshops as well?
If you have 3 groups who can access electricity, then we should think about
setting up a small posho mill - 6 to 8 kw only. Will the three
groups with access to electricity be within walking or short bicycle distance of
each other? If so, one such Posho mill can serve them nicely. It will greatly
ease their burden of mixing and blending materials and in fact will lower the
production cost of the briquette, (electricity and operating costs of
the posho mill, all in). All you have to do is increase the screen size to 20-25
mm holes. The shops sell these regularly: they do not have to be made up
specially.
The TMC is designed to be hand operated. It works on the assumption
that the operator will have to be making frequent changes in direction.
It also is desigend to run at a relatively slow speed and requires
frequent stoppages for manual clean-out--hardly the ideal thing for a
motor drive! Look forward to the challenge but we do not have to
re-invent the wheel: We have now established the capacity of a local
factory to supply a TMC from here. I suggest you get one down from
Kampala so that it can be copied quickly there.
March 29, 2007: Tips for TMC Construction - From the Experts!
To provide guidance to the engineer producing the TMC in Dar es Salaam for the Lushoto project, Mr. Richard Stanley of the Legacy Foundation provides these hints:1) The frame should be very rigid around the bearing support for the rotor, the legs could be of anything but the actual housing frame must be rigid.
2) Use good sealed pillow block bearings, not sleeve bearings/simple bushes. The rotor disk has to hold a tolerance of 2mm lateral wobble maximum.
3) In building the rotor you can start with one rotor disk. Brace it with diagonal rods (8 to say 10 mm re bar or what have you). These can remain inside the rotor. Once you have one disk aligned perfectly, only then do you do the second disk by cross bracing it accordingly.
4) The toothsets are the trickiest part. The left and right inclined toothsets are mirror opposites of 164 mm length. The non inclined toothsets (used for the front and rear of the lower housing and for the stabiliser bars for the lower screen and upper screen / filters are 160mm length.
The inclined toothsets must pass smoothly through the fixed toothsets. This means that the inclined toothsets will have to have a slightly greater spacing than the fixed toothsets because they are inclined. (About 2.5% greater spacing than the teeth in the fixed toothsets in fact.)
3) The blades for chopping can be fixed so that they do not slip. This will make it far easier to construct them. Instead of "L" shaped hooks or harnesses for restraining them, you can use a simple loose wire hoop made of coat hanger wire. The hoop passes through the rotor disk behind the blade. When the blade is engaged cutting the hoop lies loose. When you want to restrain the blade you press it back to touch the rotor disk, then swing the hoop out over the blade tip. The blades themselves need to be fairly stiff. The standard panga blade needs to be reinforced a bit--you can do this by welding a ring onto the blade center of say 15 cm OD.
Make sure you use harden steel for the anvil (we used a section of LR spring) as you do not want to have to be removing it to sharpen it all the time. (In fact we just welded it onto the frame knowing that the panga blades would go dull before it became dull.)
5) The upper hopper and upper housing should be made to the widths specified. This allows you to invert the hopper and slip it down over the upper housing to make the machine very compact for easy transport. Further, the hopper should merely be bolted onto the upper housing as it is rarely removed.
6) The lower screen however will have to be easily opened by use of a hinge and snap lock mechanism as shown. I will send you details in a day. Do not mount the lower screen yet.
|
