[M-man]

Is it possible to cut the outer contour without any need of machining after ?
The part is made of aluminium and the heigt is 26mm (about 1")..

[InspirationTool]

That looks like a timing belt pulley?

The answer is maybe. I think you would need an active (tilting) head jet, and to go slow with the cutting for a fine finish. You would have to get a quote to see if it would be a cheaper than what you are doing now.

Also, there is a wide range of quality depending upon operator skill and attention. Waterjets have a habit of leaving gouges in parts depending upon grit quality, cutting method, and nozzle replacement.

-Jeff

[One of Many]

Highly unlikely from my experience.

First, there is fixturing to align a blank to a wandering jet. This would make it tuff to keep the cut relative to the center and square to the face. Next would be stream quality over time on thicker parts. As the jewel and nozzle wear will change the kurf width and taper, consistancy will be problematic in the small radius.

If you tried making some blanks, then complete the insides to the outside cuts. Depending on your application you might overcome some of the above issues. I have cut 1" with near zero taper, but fine detail in a profile does not always work, rarely will it be 100% round.

DC

[M-man]

I was thinking of cutting it out of a plate and then do the machining. At the moment a have a special tool and cuts the gear in the lathe, but it takes some time to machine and the result arent always 100%. If it was possible to grind the right profile to a carbide mill I would prefer to machine the whole gear inte the lathe.BUt This is a project that I spend lunch breaks on so buying expensive tools isnt a option..

[Zombiestomp]

You said you are cutting the gear in a lathe ,Im assuming by lathe you must have a machine with live tooling ? If the part in the picture is what your making?If I knew what other Machines you had in your shop , for exsample maybe a Mill :} I could help you finish that part PDQ :::::::

[ironDigit]

i thaught waterjets,plasma and lasers only cut all the way true and are unsuitable for pocketing so i guess a lathe and mill would be much more reliable allthough i'ld consider doin it all in the mill so you'll only have too chukk up once and won't lose your center when movin from lathe too mill a waterjet would be nice for blanks i guess

[StealthDumpKits]

I'd waterjet the blanks out of a large plate as close to finished as it's capability allows. Then run the rest in a mill. I bet a couple Fadal 6030's with tsudakoma five axis tables and proper fixturing could blow these out.

[M-man]

The part are machined from a 120mm solid bar and then cutted off, all the machining is done in the lathe..It takes too long time to cut the outer contour, at the moment I have a tool that "draw" the profile and it takes a lot of passes for everey gear. I should prefer to us a special grinded mill and produce the gear by milling from the side, milling it from the face would keep the speeds and feeds down coz the mill used then should be like dia 1/8"x 1 1/2" long. I dont think a solid carbide mill at that size would last very long when milling speed in the machine is only 4000rmp.

Is it possible to get a carbide mill grinded to this profile??

[StealthDumpKits]

I'm not a manufacturing engineer, but the proper CNC cutter grinder should be able to cut that profile. If I had to make these parts, out of bar stock, I'd do as much as possible on a three axis live tool lathe. My only concern would be damage during the part off cut. I'd rather run 'em on a two axis lathe, fixture the part on a CNC vertical mill, then run the bolt pattern, countersink, rigid tap, and external profile. Based on the assembly picture, I assume we're looking at an adjustable camshaft timing gear?

[webcruiser8]

Waterjet is CNC controlled. The accuracy has 3 aspects:
1)
The control accuracy: whether servo or stepper, the smallest displacement.
2)
The repeat accuracy: by the name you know is how accurate it can repeat itself
to the same position.
3)
The last one, part tolerance. This is really affected by many reasons: CNC is one,
the size of orifice and nozzle is anohter, their alignment, and cutting speed, the grit of abrasive, and the curve of the part, all take part in the final tolerance. In general, it should be somewhere about 0.1mm or (0.004")

[leaghtristan]

using a water jet you would get it really close but you wouldnt be able to just bolt it on. the part would have to be finish machined after wards. i run a omax 55x100 table with a tilta jet. that would work but as i said they would need to be finish machined.

[JerryFlyGuy]

I guess it would depend from one machine to the next. I'm involved in a project right now that is 99% 304ss and we're cutting holes in 0.375 thru 0.75" 304ss plate and then tapping them out.. no drilling req'd. That is one side of the equation when it comes to WJ accuracy.

my 2 cents..

Jerry

[Geof]

I guess it would depend from one machine to the next. I'm involved in a project right now that is 99% 304ss and we're cutting holes in 0.375 thru 0.75" 304ss plate and then tapping them out.. no drilling req'd. That is one side of the equation when it comes to WJ accuracy.

my 2 cents..

Jerry

It depends on the thread size but holes for tapping can vary by plus or minus 10% on the nominal size and still be quite acceptable. How big are your holes, the variation your parts can accept may be well beyond what is okay for a toothed pulley.

[JerryFlyGuy]

We're running mainly 3/8 and 1/2" holes through-out some are a bit larger, none smaller. I'd think it's safe to say that you'd never cut the entire pully w/ a wj as you need to pocket the center and bore for the center shaft. At that point you might as well clean up the part in the same setup as you're already there anyway.

The wj spec's I'm working from [memory as it's at work] is +/- 0.002" in 1/2 to 3/4" pl.

I'll have to look it up again and see... it was not very much.. I was impressed to say the least.. also it's worth noting that a precision cut like that is worth about 3-4x more than a standard 'qual-3' [or worse] cut.

YMMV

Jerry

[M-man]

There were no need to cut entire pulley in waterjet, just the theeths, but the parts were machine in the lathe with a hand grinded tool to produce the tooth profile. It worked OK but it could have been machined with some faster method. The pulley project is completed with good results.