MetalworkingFun Forum

So what's it for?

Last weekend, I dropped into my favourite tool store to see what I could use my birthday gift card on. Nothing I needed, but I saw a 20-ton shop press that was covered in "Does not work" stickers. Regular $400 on for $150 - no warranty, as is.
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It's hard to resist an orphan, especially when it involves a challenge. The list included a ram that would not retract (Fred had pumped it down with a 10-ton pump from a porta-power set) and a pump that did NOT work.

The ram was relatively easy - the internal tension spring wasn't attached at the top end. Poor design, poorly executed. They aren't known for full retraction, but will pull up from the work when the pressure is released. Good enough for me.

The pump was another story. On the inlet from the reservoir, the steel ball check valve was above both the tank hole and the hole running to the piston chamber. Nothing to stop the oil from getting pushed back into the tank when the handle is brought down. I drilled the hole for the ball down between the two holes and set the ball with a punch.

There was no check valve after the piston chamber, so the oil came back as soon as the handle was raised for the next stroke. The passage wasn't even machined to take one.I drilled down to allow a 1/4" ball to be added, with a spring between that ball and the ball valve for the pressure release screw. That allowed me to get some movement out of the ram, but not enough to be useful.

Today, a morning thunder storm convinced me to stay in the shop and replace the pressure release valve and final check valve with larger ones. I used a 1/2"-20 bolt for the new valve shaft and a 7/16" ball for the release seal. The old 5/16" ball from the release valve became the new pump check valve. Here's the old shaft beside the new one (installed).
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I had to do some tweaking, but ended up getting nearly 15 tons out of it. At that point, the high-pressure bypass valve opens. If I really need the whole 20 tons, I'll fine-tune the HP valve. For now, it has a LOT more power than my 3-ton arbor press. Definitely left an impression on a piece of birch plywood. BTW, the hose clamp on the ram was so I could keep track of movement, when there wasn't much to see.
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(06-29-2013, 08:43 PM)TomG Wrote: [ -> ]I used a piece of drill rod and turned the taper leaving a temporary full diameter section on the end. Then I grabbed it in the mill vise and milled the tapered section exactly to center to create a cutting edge, removed the temporary end and ground a little relief on the end so it would cut as well.

Tom

Tom, could you post a pic of the flip side of the reamer showing the relief you ground?

Willie,

You are looking at the relief. This type of reamer is commonly used in watch and clock making. All they are is a pin (tapered in this case) with half of it cut away to the centerline, to create sort of a half moon shape. As long as the cut away part is exactly on center, they will cut and make a very round, very precise hole. A lot of guys use this technique to make chamber reamers, because they are so easy to make.

Tom

Darren,

This fixture will be used to modify a fine point Sharpie which will in turn be used with one of our instruments, an incubator based microscope called IncuCyte Zoom to mark areas of interest on the bottom of a microplate. This isn't one of my projects, so other than designing and making any required fixturing I'm not really up on all the technical details, but that's basically what it will be used for. I'll post some pics of the fixture when it's finished next week.

Tom

Thanks Tom. I was curious as to the hand wheel, as if the sharpie is on the centreline, turning the hand wheel wouldn't actually do anything. Slightly off centre would produce a nice little circle though.

Darren,

The fixture is to modify the Sharpie. It will cut it to length, thread the end of it, trim the wick to length and drive a set screw into the cut end to seal it. Once the Pen is modified, it will be used to mark microplates. The modified Sharpie is the end product.

Tom

(06-29-2013, 08:43 PM)TomG Wrote: [ -> ]...and ground a little relief on the end so it would cut as well.

Tom

It's a "D" reamer right? I was just wondering what kind of relief you put on the end of the reamer? 45° chamfer? Full width or half width? (So this half-wit can understand?)

FINALLY got around to finishing my firewood. 29 here today so it was a chore
Got a record breaking (and back breaking) load this year, measures out at 32 1/2 cord, almost 11 bush cord in Steve's terms.


This plus another four cords that wouldn't fit at the end.

Holy crap that's a lot of wood. I'll bet you're glad you got it done though.
It's hot in Minnesota today also. It got up to 89F. Not nearly as hot as it's been in the southwest but hot enough for this old fart to fire up the air conditioning.

Ed