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lightweight vent panel scratch build( I hope )


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Progress slow but progress all the same started the top former started off with a piece of 40mm plate 150mm wide and about 1500mm long cut off the section I need with a 9" angle grinder really going to have to think about buying a band saw

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Then started milling a 15mm deep shoulder on one side done and part way through the second long side you can see on the photos that my mill will only go so far and then I have to set up again do some more later as I'm starving and grass needs hoovering regards Stephen 

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Damm this is a cool thread, some very nice work 

I hate to be the bugger who has the negative comment and I hope I'm wrong..... but I don't think its going to be as simple as pressing that.....
Remember my silly little wire racks I went way over the top with, the large special dimple dies in the center.... they were only around 120mm dia and a I think a 7mm depression. It was maxing out my 60 ton press and it didn't form properly and tore/cut the alloy sheet, the steel didn't tear but still didn't form fully.... my press is made around a Chinese bottle jack so its anyones guess what it is actually maxing out at  

If it helps I found prestretching in a sandbag or stump so the die did minimal stretching worked for me but it left a pattern on the finished surface.... potentially I could have planished the prestretch then done the pressing and it should have come out smoother 

Looking forward to tomorrows results 


 

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Nothing negative from your input I would call it constructive criticism and with the skills you have I'm all ears if it doesn't work on my press I'll take into work and try it on that press I could even knock up a framework and try a 300 tonne jack but i would rather it worked at home thanks for your input regards Stephen

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Was going to offer to try it on mine if you wanted but it sounds like you've got a suitable press locally.

Mine is somewhere around the 80t mark and most definitely not made from Chinesium. The previous owner thought the frame was close to Victorian era and apart from the hydraulic fittings everything is measured in inches (the four nuts holding it together are 3" AF). It's certainly not struggled with anything I've put in it yet.

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I swear there must be some unnatural gravitational pull experienced by the locals round your area, Ed. Are they all, on average, a couple of inches shorter than the rest of the country?

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I'm not that bad compared to some people*! I think I've only just acquired my first tool (if you exclude the JCB and 6x6) that's over a tonne.

Little 8x4ft ex surface table for a workbench. Chap I bought it off recons it's about 1.2t, certainly noticed it on the JCB.

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*have a look at spencer427 on mig-welding or Bob (8ob). Bob's got at least 4 hydraulic presses at my last count. Just posted a picture of 4(!) 350+A welders.

Anyway,you, enough derailing of Stephen's thread!

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So failed but not miserably  believe it or not I couldn't find another bit of 3mm so tried a test piece with 2mm

The good

I got the shape I wanted and my press did it comfortably enough ( thanks for the offer Ed ) although on one end I did give it a wee shock with a big hammer

The bad

The end sections split and my top former is not wide enough so I had to hammer some dimples out

Conclusion

I think it can be done and will try again with some 3mm I used cutting oil as the lubricant but I think something PTFE based might give more slip, 3mm plate might stretch thinner and therefore not split also I did not anneal the alloy so was not guaranteed to be in its softest most malleable state photos for your perusal below any advice gratefully received as always regards Stephen 

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1 hour ago, Anderzander said:

ūüėģ is that for changing the tyres on ships? ūüöĘ

Damn when did they start running on the roads potholes are gonna be worse on a serious note 300t jack is used to lift a 60m 4m diameter rotary kiln full of refractory so support rollers can be changed regards Stephen 

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Had another shot this time with 3mm but only enough to form one end still split the sheet but not as bad still formed easily enough and you can see on the cross section of the form there is virtually no shrinkage of the plate 

Another conclusion 

I used a scabby bit of plate with paint on not the best clean will be better also again not annealed. I think if I round the edges on the short ends and corners it will allow the material to flow better another thing with the 3mm there was less deformity  out with the former requiring only a little bit of hammering to straighten up all in all I think I'm on the right track  and as the thread title says "I Hope" regards Stephen 

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how much clearance do you have between the punch and die around the edges ? 

proper candle wax might make a good drawing lube 

Using Aluminium of the best grade for deep drawing (and new) will probably make a big difference to the splitting , the oblong hole you cut in one of your pieces will also help around the ends . The edge of the oblong needs to be good and smooth with hole saw cut radii in the corners - the smooth edge reduces stress raised points that start the tear .

doing it in two stages with an annealing between could also help .

Great fab as always Stephen , your metal pile must be quite the thing , not many of us have 40mm plate in the corner¬†‚ėļÔłŹ

Steve 

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My metal pile can get a bit silly,40mm plate was getting scrapped at work so I got it originally as something  for my milling machine just in case same with snapped shafts at work I ask and usually get so in that respect I have sections of shaft laid around up to about 120mm .Clearance around formers is 3.2mms each side with a fraction more at the ends, never thought about candle wax I have some more 2 mm aluminium so I guess I will try annealing and see what that turns out like thanks for your input regards Stephen

Edited by Stellaghost
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With that clearance you are in deep drawing territory , something around 5mm all round would be more appropriate for 3mm . 2mm would give a similar clearance to material thickness ratio with your existing clearance . 

The radius around the form edge of the punch needs to be very smooth too and maybe R3 at least 

Would be interesting  to see what 1.2mm Zintec would come out like . @daslandroverman was developing tooling for Series upper vent panel inner and outer skins iirc- there is a thread on here somewhere 

Steve

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5 minutes ago, steve b said:

With that clearance you are in deep drawing territory , something around 5mm all round would be more appropriate for 3mm . 2mm would give a similar clearance to material thickness ratio with your existing clearance . 

The radius around the form edge of the punch needs to be very smooth too and maybe R3 at least 

Would be interesting  to see what 1.2mm Zintec would come out like . @daslandroverman was developing tooling for Series upper vent panel inner and outer skins iirc- there is a thread on here somewhere 

Steve

I could sharp try some mild steel or stainless regards Stephen

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8 minutes ago, Stellaghost said:

Excuse my ignorance what is zintec regards Stephen

Just a trademark / brand for what is basically pre-galvanised mild steel. Not sure if there's a difference between galvanising vs. zintec but it's basically the same thing.

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32 minutes ago, Stellaghost said:

Excuse my ignorance what is zintec regards Stephen

Zinc coated mild steel sheet , it's grey in colour and weldable as is , but welds better cleaned back a little . 

very common with repair panels such as footwells . It paints really well too . 

A test with 1.2mm ish steel would be the same 

Steve

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Slightly silly suggestion but would it benefit from having some heat applied to the forma via a blow-torch? I'd have thought the latent heat capacity of the forma would retain the heat quite nicely.

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Success  of sorts  rounded off edges of former a bit more  and tried with a piece of 1mm stainless worked but material rippled quite badly out with former

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This time back to 2mm aluminium but I polished the surfaces and gave it lashings of oil results are much better photos show detail of all corners now shower time as I'm covered in oil but quite happy regards Stephen 

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Oooh that's neat... I wonder if the punch part needs 2 sections, so the 1st bit clamps down on the outer to prevent crinkling before the centre forms the shape?

Lots of videos on YouTube from industrial processes like this that might give you some pointers as to how they manage it in production but it certainly feels like you're getting ever-closer to the right answer.

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