Drilling bronze valve cages. Not happy

BaronJ · Mar 17, 2014

GWRdriver said:
Assuming this is for a steam engine, the valve "cage" is unfamiliar to me, could you please clarify? The two bits which often need this treatment I known as the valve chest and the valve yoke. For those two I've never found a reliable way to do this in small sizes, the overhang is excessive, so I would center (Slocumbe) drill to depth, ream, and hope for the best. If the drilling face is milled flat and perpendicular drawn bronze should not need to be annealed.

Hi Harry,
I wonder if Bullpeters means poppet type valve cages !

Walltoddj · Mar 17, 2014

BaronJ said:
Hi, Thanks for your notes.

I agree about the speed. I did try the motor with no load, and it screamed like a banshee. Virtually no sparking from the comm, so it seems to be electrically in good condition. It has ball races at either end of the spindle without any detectable play.
I did try running it from a variac and the speed varied smoothly without any sudden jumps.

The grinding wheel that I propose to use is a 5" X 1/4" flat one that is rated for 5000 rpm. I have collected all the parts to build a triac speed controller, so I should be able to vary the speed from almost a standstill to its maximum. What did surprise me a little is that there is no fan to cool the motor. At the rated 1200 watts, nearly 2HP, I would have thought that a cooling fan would be mandatory.

I started welding the motor mounting plate to the baseplate today. I will have to take some pictures before I go any further.

The tool post grinder I'm building uses a Router Motor at 20,000 rpm you need to make pulleys to get to right speeds you need for the wheels you will be using.

Todd

Hopper · Mar 18, 2014

Another old dodge to help get a drill bit to drill true without running off centre is to take a blank lathe tool bit and grind the end flat and square, then hold it in the toolholder. After centre drilling the workpiece, use the piece of tool bit as a steady for the main drill, winding in the cross slide until the piece of toolbit just touches the drill bit, before you have moved the drill bit in to the work.

I suppose if you have a travelling or fixed steady, it could be set up to provide the same support for the drill bit.

Or try using a short stub drill instead of a long wobbly one. Old broken drill bits are ideal to make handy stub drills out of. If its a deeper hole, go as far as possible with the stub drill and then use the longer drill to achieve final depth.

bullpeters · Mar 18, 2014

yes he is talking about poppet valves. i dont know what type of bronze, maybe it wasn't even bronze. gunmetal maybe. Any way i have gone thru a good stick of it and after hitting various things with a hammer and swearing, decided to leave valve cages until i find something a little more friendly to use. The metal would turn up a treat but drilling a 1omm long 4 mm hole??? forget about it

BaronJ · Mar 19, 2014

bullpeters said:
yes he is talking about poppet valves. i dont know what type of bronze, maybe it wasn't even bronze. gunmetal maybe. Any way i have gone thru a good stick of it and after hitting various things with a hammer and swearing, decided to leave valve cages until i find something a little more friendly to use. The metal would turn up a treat but drilling a 1omm long 4 mm hole??? forget about it

Mmm, sometimes we don't always see the obvious. 10 mm isn't a deep hole at 4 mm diameter ! Now at 2 mm diameter its starting to get to be a deep hole...

I would be really tempted to grind the drill so that it has a square end and very little rake. Or as someone suggested an end mill.