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Mobile vice and small anvil / welding table 
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Bought the hydrochloric acid to pickle the mill scale off the table with:

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And started on another tangent related to finishing this off: viewtopic.php?f=15&t=2877

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Sun Jul 07, 2019 2:56 am
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Way back on page 1 I wrote something like the following, but with less detail:

930 table work height
220 vice height
1150 vice jaw work height
50 thick table
240 high drum
160 high hub (to step pipe sits on)
930 - 50 = 880 bottom of table plate
240 + 160 = 400 to start of pipe/tube
880 - 400 = 480 tube plus flange length

But I got the tube cut at 480 itself. So to keep those measurements I will either need to trim the tube by plate thickness, cut a hole in the plate for the tube and weld both sides, or go plate thickness higher.

I've selected the plate and it's 16mm by 250 by 230 so do I go to 946 table and 1166 vice jaws? Or bore a 142mm hole in the plate and weld top and bottom? Or shorten the tube?

For the lower disk and inner disk, I want something with a tiny bit of flex, so I'll be using the only suitable thing I have which is 12mm. The strip is 141mm wide and from an earlier post the lower disk needs to be 102mm min, and not exceed 160mm. But looking again, at 45 degrees to that limitation is a much wider space, over 200 free, so I'll clean up the edges, cut a piece off 140 wide, drill a 14mm hole in the middle, and call it good. Diagonal will be 1.414 * 140 = 198mm, so we're good, perfect even. For the inner disk, about 127mm IIRC. Worst case I'll "hand form" it with a grinder until it's snug, no *real* need for precision on that.

Went down and played with the existing number 4 vice on the bench and don't really want it any higher, so I'll find a way to cut a nice hole out of it to match the tube. Even if I have to hand file it.

Top plate and space for bottom disk: https://twitter.com/FredCookeNZ/status/ ... 9420520449

Image

Image

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Sun Jul 07, 2019 5:45 am
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Now, thinking about the flange and the vice and supporting the piece of 20mm plate that it bolts to securely and stiffly I decided that I should run a couple of thick deep sections across the fasteners in the top plate, and stepping up into the table if there is any (due to balance point), and then to the bottom of the 20mm and bolting securely to that, too.

Roughly marked out (inlined below): https://twitter.com/FredCookeNZ/status/ ... 3395694592

50mm thick table, plus 16mm thick plate, minus 20mm thick plate, equals 46mm step up from fastening surface one to fastening surface two. The remainder of the piece needs to be amply stiff, so minimum width is 100mm. Thus options are:

100x20
100x25
130x20
130x25

Or something smaller and spacers instead of cutting to make the step up. But that would look messy/cheap/untidy/sloppy to me.

100 gives us 54mm of meat remaining and 130 gives us a nice 84mm of meat.

20 requires M10 (5/side) or M12 (4/side) and new taps as I don't feel the 3mm per side that M14 would leave is enough meat left over.
25 with M14 would leave 5.5mm per side which is ample. M12 would yield 6.5 per side which might be even better. M10 7.5 per side which feels excessive.

M14 washers are about 30mm which would look silly even on 25mm stock. Presumably M12 are at most 28mm, likely 26 or so, which would look mint on 25mm stock.

I think I might pull in a favour and get the exact heights dialled in by way of a milling machine. Will give me nice flats for the fasteners and table surfaces alike.

Image






Centre of gravity calculations.

50x450dia steel weighs in cm (7.85 * PI * (45 / 2)^2 * 5) / 1000 = 62.42 kg or a little less, centred on itself
200x220x20 steel weighs in cm (7.85 * 2 * 22 * 20) / 1000 = 6.9 kg
vice weighs 32kg
vice plus plate = ~39kg centred on the plate.

Datum = edge of table
Units = cm and kg
Moment of table = 62kg * 22.5 = 1395
Moment of vice/plate = 39kg * (45 + 11 = 56cm) = 2184
Total moment = 3579
Distance from edge of table to CG = 3579 / 101 = 35cm, 350mm, 100mm from the other edge of the table.

IE, with the top plate hard up against one edge of the table, it'll still be vice-heavy, especially adding in the ignored under-brace weights.

But given the base is about 400mm wide, and substantially heavy, it won't be a problem stability wise. Excellent.

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FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Sun Jul 07, 2019 11:16 am
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