WaterJet advice needed

JTknives

JTknives

Blade Heat Treating www.jarodtodd.com
Knifemaker / Craftsman / Service Provider
Joined
Jun 11, 2006
Messages
8,633
Been on the phone calling water jet places all day and now have more questions then I started with, facepalm.
Most places gave me a quote over the phone when I provided the total cut length and material thickness. But all of them wanted to know the finish I wanted. I guess perfect finish is not in there chart lol. So anyway 99% of the people I talked to said its a scale from 1-5, 1 being a fast part off cut and 5 being a very nice finish cut. But the price goes way up with each number jump. The knives I'm doing have 10" of profile cutting and 2 1" finger holes. My first thought was finger holes get a nice finish and profile gets a medium finish of say #3. But the question becomes this , is the finer finish in just the finger holes worth the extra couple bucks per blade. Thy are cutting 30 blades at a time so a few bucks adds up quick. The 2 quotes where: profile #3 and holes #4 was $6.50 each and a #4 on both was $9.25. But if I switched everything to a #3 I'm guessing it would drop the price a good bit more. Considering doing 10" at a 4 and not a 3 bumps the price $2.75 I would think because the holes are just over 6" that would be .6% of the 10" #4 price increase which would be a $1.65 making a #3 on everything $4.85
Now this is just assuming a lot and I have sent an email to the shop to ask what it would cost.
But will going to a #3 be more trouble then it's worth considering it's a finger hole and hard to clean up. In the past I use sand paper wrapped around a rod in the drill press and it works great for keeping everything square. But if it takes a 1/2 hr to clean it up then the saving is not worth it on 30 blades.

Sorry for the crazy rambling on I was kinda just thinking out loud. Thank you for any advise you can provide.
 
Another thing about this shop is thy will provide the material. Thy get most of there D2 stock from flatground.com which is where I was planing on getting it from anyway. I think this makes more sense as I just order the number of blades I want and thy do the rest.
 
Finish cut means less kerf and less bumpy. I don't care what anyone says. You will never get zero kerf with water jet, so you will have to "fix" it anyway. You probably want to bevel the finger holes on both side anyway, so no biggie there, just bevel more on the "smaller" side. Just have the blades cut a tiny bit larger and clean up the edges on your grinder. I can tell you from experience that a horizontal grinder would be easier.Also NOT having any radiuses of like 1/4 inch also make live a lot easier. As for extra work not being worth the money, you are a knife maker so you time is worth nothing, but $75 to $90 in added costs is. :D
 
Just cutting
 
This is the knife I'm making.

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12729311_10209331756957924_6153907284744197162_n.jpg
 
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I would probably just get a few of them with different degrees of finish and decide which one suits your needs best. The only way you're really going to be able to tell is to get them in hand. I'd probably error on the side of getting a lower level finish done at first, especially if I had a surface grinder.

Hell if you were gonna do a ton of these or water jetted pieces in general, you might look at getting an industrial grade abrasive tumbler to finish them. Then you could just get them cut and then chuck them in there.
 
I would ask for cut samples. Take a look at these pics to get an idea of what they are talking about:
http://www.waterjetboston.com/wp-content/uploads/2013/04/Waterjet-Cut-Quality.jpg
http://www.waterjets.org/images/inline2/q12345_Photo_labeled.JPG

I suggest you go with your gut feeling and get a high-quality cut in any areas that you can't clean-up.

The bad news is that these cut quality options are software settings, not guaranteed results. What you actually receive is dependent on a number of factors that literally change by the hour, because as the waterjet cuts, its consumable parts (namely the orifice and mixing tube) wear. As they wear, cut quality deteriorates. Also, cut quality is highly dependent on the gap between the nozzle (mixing tube) and the material. On some machines, this is automatically set, but either way, if the gap is wrong, the cut will be crappy.

Laser has similar problems (lens integrity and alignment, nozzle integrity, and standoff accuracy). On either machine, a good operator will visually examine the first part (and subsequent parts) and make a judgement on the quality of the cut. Hopefully the guy running your parts is a good operator.

Tilting head ('dynamic') waterjets do a great job of keeping the cut perpendicular, but keep in mind that it is perpendicular to the machine's rails. The cut won't be square if your material isn't parallel to the machine rails - which can be caused by warped material, improper clamping, and/or machine bed slats that are not parallel to the cutting head's rails.

The best, but not the most feasible, way to protect yourself is to specify an minimum surface finish and/or dimensional tolerances that define an acceptable cut. For example http://www.gdandtbasics.com/profile-of-a-surface/ However, you will need a way to inspect the part, which generally would require a CMM.
 
Regardless of the cut quality, you will still need to clean up the edges. A dynamic head will help but not completely eliminate this.

I would go with a 2 or 3 quality cut and just undersize my holes. They can be drilled to size afterwards.
 
I had some folder blades and liners waterjetted. The cut quality can vary but on certain areas the kerf will have a slight bevel to it depending on cut direction and feed/speed. for the knife pictured I wouldn't go for the highest cut quality as I don't see any areas you can't clean up. on my folder liners and blades there were areas I didn't want to or couldn't clean up due to tolerances. I HAD to get the best cut possible. I had slots and holes cut. All holes were undersized, then reamed or tapped to fit. It really does just pay for itself in bandsaw blades and time.
747815BD-14A7-4052-A487-6CAB7931A582_zpsp2vxi70r.jpg
 
We've worked with more than 20 waterjet cutting shops. The best by far has been Leading Edge Fabrication:
http://www.leadingedgefab.com

Their machine has a dynamic head. When the material is cut the cut is 90°, not angled. Mark (the owner) posted a photo of 4" thick titanium with a machinist square against the edge. It matched the square. The edge still must be cleaned up after cutting.

They also can provide secondary machining operations.

Chuck
 
Well mark and I have been playing phone tag over the last few days. But another place got back to me with an even better price. The will do there fine finish on every surface which is one step below there best finish for 6.70 a blade.
 
Yes, Mark is awesome, he's an obsessive craftsman who delivers what he promises. He's also a collector of fine pocket knives, and understands what it takes in our field to be productive.


From what I've seen from my friends, whom have done anywhere from one-offs, to multi thousand piece runs, I think you'll be making a mistake if you select based on price. Do you buy the cheapest wood, cheapest belts, or sell the cheapest knives? Mark competes on quality, and delivering on his commitments, and this is in seriously short supply in the industry you're flirting with. Everybody I know that's dealt with Mark has nothing but great things to say about him, and most of them have tried numerous other outfits.


Good luck though.
 
Yeah I'm calling him agian in the morning. I don't mind paying more for quality and it's even better that he knows what we as knife makers expect. My big fear with un tested shops is them scrapping hundreds of dollars of steel becaus to them that finish should work. I still need to keep an eye on price as I'm trying to keep these at $75 each with a kydex sheath. If I can do that with marks cutting and peters heat treat I'm golden and could not ask for more.
 
When we consider waterjet companies, price is not our first criteria. We've learned by experience, it is better to pay more and receive what we want.

It is very frustrating to pay for materials and cutting, and throw everything away because the job (cutting) was not done correctly. It does not matter if the materials are replaced or if you are not charged for cutting, you will never get the time back.

Chuck
 
Alpha Knife Supply said:
When we consider waterjet companies, price is not our first criteria. We've learned by experience, it is better to pay more and receive what we want.

It is very frustrating to pay for materials and cutting, and throw everything away because the job (cutting) was not done correctly. It does not matter if the materials are replaced or if you are not charged for cutting, you will never get the time back.

Chuck
Click to expand...


Not only that, but from what I've seen, meeting schedules (even the ones they set) is a big problem with most of these places. They want the extra business, but when the shit hits the fan, the biggest, loudest, customer takes priority, and the rest get brushed aside.
 
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