John Olsen’s Unimat Belt Drive

[Neil WyattModerator @neilwyatt]

As promised, plans for the belt drive in MEW 168 are at http://www.model-engineer.co.uk/unimat

Neil

[Neil WyattModerator @neilwyatt]

Download full plans

[JasonBModerator @jasonb]

Neil, seems to be a problem with the PDF files as the drawings are missing the dimensions

[Neil WyattModerator @neilwyatt]

The dimensions are there, but in a very tiny font.

When importing to TurboCAD all the dimension lines were off the page and the dimension numbers were tiny. I was able to fix the lines, but not the numbers.

They are readable if you zoom in.

Neil

[JasonBModerator @jasonb]

1000% and good eyesight is needed but some of the dim lines don't seem to go to any feature on the drawing

[John HinkleyParticipant @johnhinkley26699]

Neil,

I think you'll find the article is in MEW 268! I tried playing around with one of the files ( Cshaft_10 ) by importing it into Inkscape and re-exporting it as a DXF file to my CAD program. The resulting drawing was MASSIVE but the dimensions, as you say, were miniscule. By scaling the drawing to a manageable size, I tried re-dimensioning it. As Jason says, the dimension lines don't line up with any intersections and thus are meaningless. One, the (almost ) width of the pulley is labelled 28.65. Seems a strange value to me. At this point, I decided that the lawn needed mowing, so gave up the idea of converting said drawings. I don't have a Unimat, so the exercise was purely one of an intellectual challenge. It could be done, but not without the required dimensions.

John

[JasonBModerator @jasonb]

My thoughts are that Neil imported a metric DXF drawing but had units set to imperial so he has a 1:1 drawing of a 32" dia pully but the font is still set to 10 or 12pt which would be fine if the part was the actual 32mm dia Big give away is that the dimensions are quite readable when zoomed to 2540%.

I have asked him to send me one of John's DXF file so I can try for sure but I can replicate similar issues by importing a drawing with the wrong units that wants to print on a 108" wide sheet of paper!

 

Edited By JasonB on 22/05/2018 17:30:54

[JasonBModerator @jasonb]

Tried it with a DXF of teh 41T gear.

If I import it with imperial units it comes up as per neil's PDF and if I add my own dimensions they are as small as Neil's. My 9.55 is highlighted and corresponds with the 9.55 on the drawing. If I try to print this to PDF it thinks the sheet is 108" wide.

Same DXF imported as metric units and same dimension added by me except this time it come up the right size and if I try to print to PDF it will fit an A4 sheet

The 32.67 dimension that does not really point to anything is actually the outside radius of the pulley but I can't find what the 18.81 and 12.81 relate to as the hole is 14 dia so not even worth trying to redimension the drawings even if I could be bothered.

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