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Mazak QT15 - Spade Drilling (coolant pressure)

Pete Deal

Stainless
Joined
Apr 10, 2007
Location
Morgantown, WV
I have a .540 dia x 11.5" deep blind hole to drill in a piece 304 stainless. I found a long AMEC spade bit in good shape for sale on ebay which I bought. I called AMEC and they recommend 150psi coolant pressure. I have a multi-stage pump. that I think I can setup. Do any of you know if the turret coolant seals will be good for 150psi?
 
if we are talking the old t2/t32ish spring system.
yeah mostly it may oozz a bit a the spot where turret contacts body but no major problems related to such. some newer and super a quick turns have a hydraulic system pron to coolant/hydraulic cross contamination(o-ring blows and loses separation of fluids) higher pressure will give some of those problems
 
Yes it is a T2. Thanks!

A friend of mine makes a black powder cannon each year for the friends of NRA dinner. It takes him a long time on a manual lathe so I offered to turn and bore it for him this year. I expect boring the hole to be an adventure.
 
Hey Pete, how did the boring turn out? What sort of boring bar setup did you use. That's a pretty steep diam/depth ratio so I'm curious what sort of bar, feeds, and speeds you went with.
 
Still have not done it. I had to get my pump setup and order some custom inserts for the drill. Once I get one job out of the way it is on the list.

I had an 11 stage pump that I used as a water booster pump one time that is like this:
https://www.grainger.com/product/DAYTON-Pump-5NYA4?functionCode=P2IDP2PCP

Supposed to be rated at about 150psi boost. Not really ideal but I have it. The pump system seems to work pretty well I am getting 100psi but I need to plug a hole in my bushing that I made to get coolant to the drill. Loosing a lot there. The standard pumps that mazak puts on the lathe only run about 20psi. I plumbed it in series with the existing pump and put a separate starter in the control cabinet for the new pump. I got a current sensing switch to detect the standard pump coming on to switch on the booster pump. Most all the controls came from ebay and stuff I scavenged over the years.
 
Well I finally got everything setup and drilled this part. Sort of a disaster! First I think I would like to make myself an id tool holder for this purpose before doing this again. When the coolant pressure gets up to about 130-150 psi coolant comes out everywhere on those mazak blocks. I'd like to figure a way to plumb right from the turret to the back of the tool. The problem with leaks is that at least on my setup I think it saps a lot of pressure that the drill could benefit from.

As for the drilling part... Allied tool has guidelines for deep hole drilling with their products. The required hole turned out to be .540" dia, 8.75" deep, material 304 ss. I followed this guide as best I could. It involves drilling a starter hole 2xD deep with a short drill first. I set out to do this and got about 1xD deep and heard "crunch". There went one of my two custom ground inserts. I shut stuff down and called it a day. The drill absolutley was not breaking chips at all- Long strings. I called allied the next day and talked with an applications guy told him what I was doing, feeds, speeds, what inserts, etc. He said the inserts I had were not ideal. Frustrating because I know nothing about picking these so called them to tell me what I needed (another guy). Unfortunately they did not offer to send me two more of what I ought to have. They did say that since I only had one part to do just go ahead and set it up for a .05" peck and a .01" retract and that should do the trick. I wound up going to .05 peck with full retract because it still was not flushing the chips always. I got through one part but I don't think the insert would be up to another. The insert they told me to use and I bought was carbide. The new tech svc guy suggested a cobalt insert with their "tiny chip" grind. So next time... Funny thing is that I read as much as i could about spade drilling here on PM before getting into this and came away with the idea that I should use cobalt. I chose carbide based on the suggestions of the first technical guy I spoke with at allied. It was a good education if nothing else.
 
Has anyone else attempted this?

I'd like to get over 100psi on a spde drill and am taking pump recommendations.

Thanks crew!

Sent via CNC 88HS
 
Has anyone else attempted this?

I'd like to get over 100psi on a spde drill and am taking pump recommendations.
Used to make cup molds for Handi-Kup. Material was 304 and the holes (blind) were about an inch diameter by maybe ten inches deep on the tall ones ?

I just used a hss bit, normal coolant but plumbed direct into the back of the drill holder, and pushed it in at stainless speeds. No pecking but maybe did stop the advance incrementally to break chips as it got deeper, but not even that for too long as stainless work hardens. Howled like a mofo, the neighbors asked me to run at night so I did, but was not really a problem. Didn't have to do anything special or weird, and learned to resharpen the tool. The little slots in the cutting edge for breaking up the chips were important, that was about it for technicalities.

Pretty much big bubbles, no troubles (except for the noise.)
 
I'd like to get over 100psi on a spade drill and am taking pump recommendations.

A good multi-stage centrifugal pump is a great solution. They are powerful and quiet. Often the multi-stages makes the pump section really long, but all ya gotta do is use a spacer of some sort to raise the pump above the top level of your coolant tank, allowing the bottom of the pump to clear the bottom of the tank by at least 1" or so, to avoid cavitation.

Grundfos is the gold standard of centrifugal coolant pumps, so you can't go wrong with one. Walrus (yeah, silly name) is a Taiwanese builder of good centrifugal pumps.

I'm cheap, so my go-to for upgrading coolant pumps is ebay.

As far as pressure goes, often it's confusing as to how the pumps are spec'd versus the actual pressure we want at the tool tip. What I do is just refer back to simple physics: the higher the amp draw, the more pressure a centrifugal pump will have.

The good thing about multi-stage centrifugal pumps is they make more pressure with more amps. And pressure is what you want, not necessarily flow. (You're only gonna push so many gallons-per-minute through the tiny holes in a drill, regardless of pressure.)

ToolCat Greg
 
What Greg Said. I since found a brand new multi stage Grundfos pump at HGR. Brand new. Can't remember how much but it was like $100 or so. I'm not 100% sure, Greg would know better, if the coolant seals on these older Mazaks are up to these pressures though. It worked for me but for most common stuff I like the low pressure high volume flow of the standard pump.
 
What Greg Said. I since found a brand new multi stage Grundfos pump at HGR. Brand new. Can't remember how much but it was like $100 or so. I'm not 100% sure, Greg would know better, if the coolant seals on these older Mazaks are up to these pressures though. It worked for me but for most common stuff I like the low pressure high volume flow of the standard pump.
For this app, I think I could just plumb directly to the drill itself. Have to be careful with turret rotation, but that's cake when you're only using 3 adjacent tools.


Thank you both!
 








 
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