Water jet taper

Hey guys,

I’m going to have a two inch hole cut into a two inch thick piece of steel plate. Not having done this before, how true will that 2” hole be ? I feel like it will have a taper but how much? Should I consider drilling it or water jet cut undersized then bore?

Better to drill it. Taper will depend on cut quality and machine and a few other parameters

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what sort of material? will a heat effected zone matter?

On that thickness it will have taper, depends on machine, how fast they run it, nozzle condition, due to thickness it will be slow so expensive to cut.

If its not critical to heat effected zone i would oxy cut it and if you have enough gas flow and correct nozzle taper will be negligible.

I used to run a waterjet.

Oxy cut by a contractor to cut up to 7" thick steel for gears, doing a profile and it was 0.2mm taper which is great for it, considering it was sand cast gear originally so 0.2 didn't matter.

had to edit must a bit...waterjet is not good for thick items its too slow and hence costly. definitely not good to 7in only a stretch at 4" surface finish is bad at that thickness speed is horrible.

It’s only a two inch thick piece of steel. But I figured there’d be a taper to it. The hole needs to be fairly true. I’m going to split the piece in half and use split bushings in it as a barrel vise. Probably better off on a mill?

just machine it in a lathe, it will only be a small piece either square or round.

The surface finish will be important as its the friction that holds the barrel so you will need to be parallel and to a good size, of good finish so no marking is done on the barrel.
You need to be good on the diameter again if its too far off its point contact again no good you need friction to work to hold the barrel.

Maybe someone will chime in on a tolerance to hold.

waterjet / oxy cut is not what you want your wasting your time and money doing it that way

On edit if you don't know this you should learn more before attempting something as critical as gunsmithing.

Go do a apprenticeship on it if you have a interest in the area before you start.

I don't want you to hurt yourself.

Thank you for your thoughts and time to respond. The vise is 4x6x2”. The hole will hold the collets or bushings for the respective barrel diameters or tapers. I’m sure it’s important to have a decent surface finish and for it to be true. I’ve only used cnc mills and lathes and this was 15 years ago. No water jet experience at all. This is being done for me as a favor and I wanted to make it easy for the guy doing it for me while still having the part be right. I figured the program would be easier to write and there wouldn’t be an issue holding the part while splitting the two piece vise using a water jet. I understand a water jet isn’t the way to go. That’s why I asked. As for gun smithing, I’m just using it to hold barrels to break loose muzzle devices. I know there’s tools not as elaborate but I’d like the option to use it later for other operations if I needed to. My question has been answered. Thank you guys again.

If everything is operating properly it should have around .002" to .003" of taper per side, so .006" total difference in diameter, smaller at the bottom. The taper is pretty constant with thickness, i.e. you'd have the same taper with 1/2" plate.

waterjet, no.

water jet can have anywhere from 0.008" taper to infinity, depending on the machine. average id say is 20-30 thou without an angled head to compensate.

i would personally drill then bore if it was that thick. 2" drill bit is probably cheaper and takes 5-10 minutes at most and done.

multiples, id go waterjet then bore to finish size. start about 1/8" undersize or more