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Some photos of my latest metal mashing project

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Some photos of my latest metal mashing project

Postby Dr.Al » 05 Jun 2021, 19:01

I started this last weekend and have made quite a lot of bits in the last week. I'm not going to do a build log for this one, but here's a few random photos in no particular order.

Can you guess what it is yet?

steel_gear_blank_600.jpg
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round_objects_600.jpg
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gear_options_600.jpg
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aluminium_spacer_tubes_600.jpg
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machining_ends_of_long_bars_600.jpg
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machining_taper_600.jpg
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aluminium_bar_bits_600.jpg
(25.52 KiB)


table_end_close_up_600.jpg
(13.57 KiB)
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Re: Some photos of my latest metal mashing project

Postby Dr.Al » 06 Jun 2021, 17:48

I guess no-one is in the mood for guessing...

Some more pictures:

small_round_objects_600.jpg
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table_brackets_600.jpg
(25.48 KiB)
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Re: Some photos of my latest metal mashing project

Postby AndyT » 06 Jun 2021, 19:55

It's got a lot of gears. Probably not a clock. Some sort of CNC gizmo?
Last edited by AndyT on 06 Jun 2021, 20:57, edited 1 time in total.
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Re: Some photos of my latest metal mashing project

Postby Dr.Al » 06 Jun 2021, 20:56

AndyT wrote:It's got a lot of gears. Probably not a clock. Dome sort of CNC gizmo?


Nope. It only uses four gears; I made more as I wasn't sure what gear ratio I wanted.
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Re: Some photos of my latest metal mashing project

Postby Trevanion » 06 Jun 2021, 21:05

I can honestly say, I haven't a clue :eusa-think:

Obviously, those two brackety looking things with the curved slots bolt to the aluminium piece with the taper on it, but I can't see what it's for exactly, especially with the gears.
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Re: Some photos of my latest metal mashing project

Postby NickM » 06 Jun 2021, 22:54

I saw your post but couldn’t work out what you’re up to!
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Re: Some photos of my latest metal mashing project

Postby novocaine » 06 Jun 2021, 23:27

Got to admit, I've been looking at it for a bit and i still can't figure it out i see what looks like a pair of motor mounts. 2 parallel shafts and a slim taper that can move through 80 ish degrees. Half of its ali, so not stressed, therefore not a break of any kind. The two shafts suggest linear, precise movement, with Zero twist. But having said motor mount it appears theres a hand wheel.
I'm at a loss.
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Re: Some photos of my latest metal mashing project

Postby Dr.Al » 07 Jun 2021, 07:51

Interesting to see everyone's thinking!

I'll put you out of your "misery", but some more photos first. Here's most of the bits I've made so far put together:

drive_assembly_standing_up_600.jpg
(26.19 KiB)


The large holes in the top plate are for magnets; the small holes either side of the central spigot (if that's the right word) are for drive dogs. The plain holes in the flat plate next to the cap screws and smaller threaded holes are for bits of steel as the aluminium in that area would wear too much.

Another view:

drive_assembly_on_side_600.jpg
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This photo perhaps gives a better idea:

first_test_with_disc_fitted_600.jpg
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The motor runs at about 3600 rpm; the gearbox slows it down to about 400 rpm. Those discs are cheap (about £5.50 each) 152 mm diameter diamond coated steel discs (available in grits 80 to 3000), that get magnetised onto the top plate and driven by the little drive dogs (5 mm diameter steel pins in the holes I mentioned earlier in this post). It's based loosely on an idea from Stefan Gotteswinter, although using bigger discs than his and the whole thing has been designed from scratch by me

The plate with the curved side on the top is held in place with four cap screws and has four grub screws that bear on the steel inserts and, between the cap screws and the grub screws, the height and angle of the plate can be laboriously tweaked to get it level with the top of the diamond disc. The table (bottom of the last picture) will eventually be attached on the side (in one of two positions) to give a reference for grinding (slowly) at angles down to 20° (@novocaine: your assessment of the taper angle was spot on!)

The aim is that I can use it for reshaping second-hand plane blades and chisels to get an accurately square end on them. Running slowly will mean it takes a lot longer than a bench grinder, but the blade shouldn't get as hot. I hate putting plane blades and chisels on the bench grinder and I much prefer the idea of something that goes slowly and has a flat grinding surface. The groove in the table will be for a fence that helps keep everything lined up as it's plunged into the grinding disc.

The flat plate on the right of the photo, once set at the right height, is there to support a tool when you're flattening the back.

When all complete it should look something like this (although I haven't designed the bit at the bottom of this picture yet, so the whole thing is just floating above the brown-coloured power supply block at the moment):

cad_model_without_bottom_detail_600.jpg
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I used it to sharpen a penknife to 3000 grit last night and it worked remarkably well - a penknife doesn't need the table, so that's about as much as I can do until the table is attached. Having played with it a bit, I think it'll be most often used in the orientation shown in the first test photo above: with the disc horizontal at the top rather than vertical on the side like in the CAD model.

In theory I should also be able to use it with my Harold Hall grinding rest for accurate metalworky grindy things, although I'll probably stick to a bench grinder for anything that involves high-speed steel.
Last edited by Dr.Al on 07 Jun 2021, 08:04, edited 3 times in total.
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Re: Some photos of my latest metal mashing project

Postby AndyT » 07 Jun 2021, 07:56

Brilliant! I can see you getting a few orders if you want them...
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Re: Some photos of my latest metal mashing project

Postby NickM » 07 Jun 2021, 09:36

I would never have guessed! Another great project.
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Re: Some photos of my latest metal mashing project

Postby novocaine » 07 Jun 2021, 14:40

As soon as i saw the first picture i was kicking myself. Brilliant and nicely done Al.
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Re: Some photos of my latest metal mashing project

Postby Woodster » 07 Jun 2021, 16:22

Interesting project. I’m wondering though if a honing jig on a 12mm rod might be a better option than using a table?

https://www.axminstertools.com/axminste ... dge-105281

I’ve got a slotted table on my belt sander and it’s not bad for some jobs but I plan to make a jig like the Axminster one linked at some point for my chisels.
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Re: Some photos of my latest metal mashing project

Postby Dr.Al » 07 Jun 2021, 17:42

Woodster wrote:Interesting project. I’m wondering though if a honing jig on a 12mm rod might be a better option than using a table?

https://www.axminstertools.com/axminste ... dge-105281

I’ve got a slotted table on my belt sander and it’s not bad for some jobs but I plan to make a jig like the Axminster one linked at some point for my chisels.


That's an interesting approach: I hadn't seen that before. I'm not sure what it adds over a table & fence (as long as the table can be set accurately), but I may change my mind once I've actually used my table! Still a while to go before I get to that point!

When I was designing mine I avoided the idea of basing it on a honing jig due to the potential speed it might remove metal. If it removes metal a lot quicker than hand sharpening (which I hope it will†, just a lot slower than a bench grinder), then the bevel angle changes as you sharpen if you're pivoting around a point. If you're sliding on a table it stays at the same angle as the table.

† I'm actually not that bothered if it is as slow as hand "sharpening" (shaping on a stone / w&d paper), although I suspect it'll be a lot quicker. What I really want is it to be a lot less effort than shaping by hand and a lot less heat-inducing / easy-to-mess-up than a bench grinder.
Last edited by Dr.Al on 07 Jun 2021, 17:48, edited 1 time in total.
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Re: Some photos of my latest metal mashing project

Postby Dr.Al » 07 Jun 2021, 17:44

This evening I made a couple of knurled knobs:

knurled_knobs_600.jpg
(26.26 KiB)


They allow me to fit the table (with some washers to take the place of the cover that will eventually be between the aluminium body and the table bracket):

grinder_with_table_fitted_at_angle_600.jpg
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grinder_with_table_fitted_at_90_degrees_600.jpg
(31.95 KiB)


I need to reduce the depth of the table, but that was expected. I'd erred on the side of too big on the premise it's a lot easier to make it smaller than bigger. At the moment it clears the disc, but only just. I'd like there to be enough room between the disc and the table to allow me to change discs (typically to a finer grit) without moving the table. It should be a very quick job at the weekend to skim a millimetre or two off the side closest to the disc.
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Re: Some photos of my latest metal mashing project

Postby Woodster » 07 Jun 2021, 18:31

Dr.Al wrote:
That's an interesting approach: I hadn't seen that before. I'm not sure what it adds over a table & fence (as long as the table can be set accurately), but I may change my mind once I've actually used my table! Still a while to go before I get to that point!


I’m not that sure myself yet until I get round to making one. Tormek and Axminster use it though and it does seem to work very well looking at the videos I’ve seen.

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