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Thread: Drill press hold down table
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25th Aug 2018, 09:12 PM #16
Thanks Bob, I am going there now!
Peter
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26th Aug 2018, 11:48 AM #17
Hi BobL,
Luv your work.
But how do you stop it rusting.
Wax or something else?
Grahame
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26th Aug 2018, 12:16 PM #18Member: Blue and white apron brigade
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Thanks
But how do you stop it rusting.
Wax or something else?
The main problem with this will be suspending the table inside the chamber - the PVC support cross pipes are only jammed in there to the extent that they can support small work piece sbut if I was to suspend the table from one of these they would just collapse. Then the falling table would knock the containers holding the acid over and make a mess.
Ideally I don't want to rest the workpiece on anything as the acid vapour may condense and pool on anything the workpiece touches.
I need an acid resistance cross piece I can screw into place across the barrel.
The nitric and hydrochloric atmosphere in the tank will eventually corrode just about any practical type of metal , and the nitric acid may set any wood on fire.
What I might do is use a steel rod and sleeve it with PVC
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26th Aug 2018, 12:45 PM #19Most Valued Member
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27th Aug 2018, 10:12 AM #20Member: Blue and white apron brigade
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I found some larger thicker PVC pipe and saw were are two indents on the inside of the chamber/tank where the external handles are welded on that I could sit the ends of the PVC into. I made up a sort of suspension jig and did a test suspension of the table inside the tank and it seems OK.
This was the result of overnight suspension in the tank. It should look rusty and it was more rusty than it appears in the photo.
I wasn't expecting too much because the amount of corrosion is temp dependent and while all the edges are corroded but only about 7/8 of the top is corroded. What is interesting is that the un-corroded bit was the deepest in the tank so is should see more acid vapour.
1stpassoutoftank.jpg
To work properly the work piece has to be very clean and I suspect I did not get all the solvent off the surface although if this had been the case I would have expected the surface to be more patchy. The other possibility is the ratio of water/air and acid vapour may not be optimised at that depth.
The next thing I found was I had to upscale the boiling in distilled/deionised water (DW) apparatus. For all my other work I have got away with a 200 mm diameter by 120 mm deep SS saucepan (I have my own set for shed experiments when SWMBO upgraded the kitchen set about a decade ago). To heat this I place it on a old electric frying pan in the shed but the frying pan was also too small to fit the table
The table is only 250 mm square so I needed a bigger pot. There were two SS baking trays in the kitchen but there was no way I was going to be able to use those so I looked on line and eventually found a decent sized one at IKEA for a whopping $14.99. Then I had to brave IKEA on a sunday arvo with my bung knee but that is another story.
In the round SS saucepan I only used enough DW to cover the parts which was usually around 500ml but to fill the pan and cover the table I had to use 4L of DW. The water should not be reused so all up I will need ~30 odd litres to complete the process, fortunately I can make high grade DW in house so I had to do that first.
Here it is bubbling away across two induction heaters on the kitchen stove - Yes I got permission to so this.
Broiling.jpg
When I pulled it out you can see the black oxide soot - I found handling such a hot heavy object is not easy so I screwed a couple of 5/16" bolts into two of the holes to make it easier to handle.
1stpasssoot.jpg
and after removing the soot - yep that's all the blackening you get on the first pass - a sort of a light/medium grey.
The more time this process is repeated the darker it gets.
1stpass.jpg
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29th Aug 2018, 01:37 PM #21
Float Vice
There is a comprehensive set of drawings for a float vice on Home Metal Shop Club of Houston's project list.
http://www.homemetalshopclub.org/new...104.pdf#page=6
Worth having a look through the rest of the project list;
HMSC Articles
Findlay
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29th Aug 2018, 01:58 PM #22
Ever since I read the OP. I’ve been thinking didn’t Harold Hall make something like this?
…..Live a Quiet Life & Work with your Hands
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29th Aug 2018, 07:07 PM #23
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2nd Sep 2018, 10:00 AM #24Member: Blue and white apron brigade
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Finished bluing the table.
It will be interesting to see how it abrades - when it gets too bad I can always reblue it.
DPTableBlued.jpg
This was 8 passes through the fume tank and used up ~40L of distilled/dionzed water. Because the weather was cold I was only able to do two passes per day so it took 4 days all up.
Anorak Bob send me a link that uses a fast, low water use, method involving hydrogen peroxide and salt as the rusting agent and reuses the same water in the distilled water boiling step.
https://thecogwheel.net/2018/03/16/v...t-bluing/'
The process still requires multiple rusting steps and boiling in water. On his vid it seems a bit messier than fume tank bluing. The H2O2/NaCl solution is painted onto the work pieces (I would use a spray bottle) and the rust developes almost instantly. The rusty pieces are then dried with a hot air gun and the resulting rusty mess is then boiled in water for 5 mins (I boil mine for 20 mins maybe this is too long).
He uses regular water but it does have a low TDS content, certainly lower that what we have here in Perth.
The last step is soaking the object in warm/hot oil.
However, it's much quicker than fume bluing - he claims 4-5 passes per hour but that seems a bit quick to me - OK maybe if you only had 1-2 parts to do.
Not sure about the quality of the black oxide finish but will give it a try and compare it to the fume tank bluing.
In the meantime I have been exploring ways of speeding up the fume bluing but will start another thread about this.
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