In my shop I would use my vertical band saw or my Evolution saw to cut into bite sized pieces. Water jet cutting would be good option, in fact, I would be tempted to have the pieces roughed out with a water jet, then finish on the mill.
Found a deal on 1/2" 4140 HRHT but it is 24 x 58 inches! I am going to see if they have a way to cut it down - maybe two strips 12 x 58. I think I could find a horizontal bandsaw with 12" cut. Or maybe several 12 x 24 chunks. Don't think I want to torch or plasma cut it - won't that make the edge harder? Maybe not if it is already HT so perhaps crack it... Could get it onto a mill table and mill it into pieces. Don't know of anything else that will work reasonably well... Ideas?
In my shop I would use my vertical band saw or my Evolution saw to cut into bite sized pieces. Water jet cutting would be good option, in fact, I would be tempted to have the pieces roughed out with a water jet, then finish on the mill.
Jim Dawson
Sandy, Oregon, USA
I checked around on the cost of water jet. there is a maker space here that has one but with membership and training I am at about $350 before I start. Machine time is pretty cheap after that. But the large CNC mill I need for the size parts I am doing is at another one. They have a cnc plasma table - not sure if it can handle 24" wide plate. From what I have read the plasma cut only affects the steel to a very shallow depth so if I just just the outside of plates it won't be a final working surface and can be ground off if I need to machine but could likely just leave the outside as is on many parts. My machinist friend said they have a water jet and that the cutting might run a couple hundred dollars which doesn't sound too bad, especially if they can do some of the other cutting at the same time. I might be able to get into the college where I took a class and use their horizontal band saw that has coolant and adjustable speed - not sure if it can handle 24" cut.
Just got back a quote on 4140 HT 1/2 x 12 x 12 plate decarb free at $157 each. For 4 plates from another source 4140 annealed same size was about $525. The HRHT 1/2 x 24 x 58 is about $250. Seeing that I need a number of pieces it seems like figuring out some way to deal with the large sheet would be the way to go.
Having a hard time finding a horizontal bandsaw big enough (24.5") and can't imagine trying to get through 24" several times on a vertical bandsaw while wrestling a 200+ lb plate. Would plasma cutter be a reasonable way to cut this 4140 HT plate? I have access to a CNC plasma table. I know it would mess with the hardness but from what I have read that is very thin (around 0.01") and could be ground off if if was too difficult to mill. I don't need the perimeter of the plates to be the working edge on most of the parts so could leave as is at least for some.
I take it carbide tipped reamers can take a bit more flex in the shaft so are less likely to break the shaft - is that the main benefit of carbide tipped? In sizes around 1/4" carbide tipped are about $47 and solid carbide are about $10 less so not a huge difference. I also see that the shanks are 15/64 which will not work well in a R8 1/4" collet (and not wanting to go to ER32 collets which would have enough range to properly grip them). Planning to use them in a drill chuck. I realize it isn't quite as good as a collet but is this any real issue? I will be using the drill chuck for the drilling so it's an easy change out to the reamer.
The only problem with plasma is the edge hardening. If you can work around that, then you should be fine. Water jet would be my first choice if available.
That's odd, normally solid carbide is more expensive than carbide tipped. But yes, the shank is more flexible on the carbide tipped and they should follow the hole better. The main reason i use carbide tipped is that they are longer lasting than HSS reamers without much price increase. I don't think I have any solid carbide reamers. I do 90% of my reaming using a drill chuck.
Jim Dawson
Sandy, Oregon, USA
Was just talking to someone at work about a shop nearby with a waterjet that should give me a good deal on cutting this up into manageable pieces. Will keep the plasma in mind as a backup....
I was surprised solid carbide was cheaper too. I have a few HSS reamers that were a little less than half the cost of carbide but I can see that if they get much use the carbide is longer life and will save money in the long run.