I.T. PUBLICATIONS

How to make a Metal Bending Machine

Description

Letters in brackets ( ) refer to drawings and photgraphs which follow.

The basic machine consists of a fixed arm (A) bolted to two pieces of channel (F), the latter provided with holes at both ends and intended to facilitate mounting of the machine on a bench or other solid surface. The pivoting arm (B) which controls the metal bending operation is fitted with a handle (E), and pivot pin (G) which can be placed in any of the nine position holes to fix the arms about the required point according to the bending work involved.

The notched angle iron bending former (L) and the material grip/former (J) were intentionally designed with sides angled at 87 1/2° to allow for material 'spring-back' when bending angle or flat to 90°.

The circle bending former (H) was originally built with a bending surface curve of 14" (355mm) radius, and when bending 4" x 3/8" black mild steel flat this gave a hoop of 33" nominal diameter. Since the aim was to produce a wheel rim of 30" nominal diameter, being that used in a standard ox-cart design (S), a new circle former of 12 1/2" (317mm) radius was built; bending trials were carried out, and after the addition by tack welding of two pieces of 4" x 3/8" (l0lmm x 9.5mm) the then total radius of 13 1/4" (336mm) was found to give a circle of the required 30" nominal diameter. During bending trials it was found that a flat section of up to 3 1/2" in length remained at both ends of the wheel rim and that there was a small amount of stretching of the material during bending; these points are dealt with in the section on 'Building a Wheel'.

At both extreme ends of the material flat sections will be observed, each of up to 3 1/2" (89mm) in length. These flat sections are cut off to leave a total length of material of 94" (2387mm).

The material is then re-inserted into the machine and the bending operation continued as illustrated. It is of assistance if the top edge of the material is marked off in 2" (50mm) steps by chalk marks to act as a guide each time the material is pushed forward for the next bend.

CONTRIBUTIONS TO BOILING POINT

Contributions are invited for the next three issues of Boiling Point the main themes of which will be:

No. 13 - Health & Safety
No. 14 - Kitchen, Pots & Cooking Practices
No. 15 - Country Issue: Kenya & Sri Lanka

Articles for these issues should reach this office by the end of July for issue No. 13, by the end of November for issue No. 14 and by the end of March '88 for issue No. 15.

There is increasing concern about the damage to eyes and general health caused by smoke from biomass fuelled cooking stoves. To judge from the small amount of written material we have been able to locate on this and other health and safety aspects of village cooking, it seems little research has been done by A.T. organizations. We should be very pleased to receive any contributions on the subject, preferably by the end of July.

TECHNICAL ENQUIRIES TO ITDG

One of the most valuable services provided by ITDG is in answering technical enquiries.

The stoves team and its associates are at your service in this way and have answered many enquiries over the last 6 years. They are ready to tackle questions on subjects such as stove promotion and dissemination; marketing and economics; production; project strategy and planning as well as technical problems of design and testing etc. Remember, if you need a detailed answer, you should give as much detailed information as possible.

Iterrnediate technology Development Group Ltd

'Boiling Point' is the newsletter of the Intermediate Technology Development Group's Fuel for Food Programme. Contributions are welcome in the form of articles of not more than 700 words with line drawings, simple graphs, etc., where appropriate. All correspondence should be addressed to: 'Boiling Point, , ITDG Fuel for Food Programme, Myson House, Railway Terrace, Rugby, CV21 3HT.

Opinions expressed in contributory articles are those of the authors and not necessarily those of the ITDG Fuel for Food Programme.

(Readers wishing to enter into correspondence with any of the authors may obtain full postal addresses from the address given above).