Jet Pump Blueprinting ?

[miller19j]

Ok Jet pump gurus I need your help
I just checked my “Tuned Performance Impeller” :rolleyes: and found that it is .005” out of round at the wear ring surface (shown in photo). I suspected that this would be the case so I ordered an undersized wear wring to go with it. I plan on turning it down so that it runs concentric with the shaft and has the clearance matched to the actual diameter of my wear ring (opposed to the advertised diameter).
Now on to my question, the impeller is anodized to help prevent oxidation. When I turn the wear ring surface down I will remove the anodizing in the process. Do I need to apply anything to that surface to prevent oxidation or can I just leave the surface bare?
Any information would be greatly appreciated
http://free.***boat.net/gallery/Gearhead_Garage/Motors_and_Drives/jet.JPG

[MikeF]

M, .005 is not that much. eek! Does the change of reading on the dial indicator correspond w/ the key on the shaft? :confused:

[HammerDown]

Your shaft may be out a couple thou. I belive up to .004 is the max run out on a shaft...mine was out just under .002 I turned mine on my shaft...where you want to check is at the front edge, I zero'ed my impellar on my shaft... Thats where you will make adjustments with shims on the shaft. Never coated my Aggressor Imp. and it looks fine after several years. I'm running just under .018 clearance at the front lip of the wear ring.
I belive .015 per side or .030 total for radial clearence, stainless Imp. can go tighter.
[ November 07, 2002, 07:54 PM: Message edited by: HammerDown ]

[jacuzer]

Miller,
Don't know if you checked this but...
remove the impeller and chuck the shaft only back up.
Check for runout between the diameter on the step and the dia on the main shaft area.
Sometimes the main shaft area runs out excessively which could cause your TIR measurement to be off (if you were using that as your reference)
If you have to cut the imp. you shouldn't need to coat it.
Kevin

[miller19j]

I checked my shaft and its runout is less than .001 I was a little disappointed at this but from what I am hearing from you guys it is pretty good. Oh by the way the shaft is new the old one was in pretty bad shape. I have not checked the front edge yet that is the next thing I will check.
But the important thing is that you guys have cut yours down and not recoated them and had no problems. I will plan on truing it up and leaving it uncoated then.
Hammerdown,
I do not have a diagram in front of me and it might be clear to me if I did, but where would you put shims to compensate for cutting the front edge back?
Thanks for the input guys!

[miller19j]

MikeF:
M, .005 is not that much. eek! Does the change of reading on the dial indicator correspond w/ the key on the shaft? :confused: No it seems to be out in two separate spots and they do not co inside with the key. I am assuming that this is a cast part and that is why it has the irregularities.
I think that .005 is quit a bit when you start adding all the tolerances up. The bowl bearings feel like they have at least that much. I am planning on running the clearance a little tighter that stock so I want everything as true as I can get it.

[jweeks123]

let's see now - you want to remove a VERY HARD protective coating so you can run with a very soft aluminum exposed to the harsh trash that passes thru your jet. sure, go for it! also tighten up those clearances so the sand can get a good shot at that raw aluminum. those guys that said to run closer to .025 with hard anodize or closer to .030 without it, couldn't possibly have experience. could they? .005 TIR? that's .0025 off center. not fantastic, but not terrible when there's a .013 gap around the impeller and it has a hard coating on it.
jw

[HammerDown]

miller19j
Hammerdown,
I do not have a diagram in front of me and it might be clear to me if I did, but where would you put shims to compensate for cutting the front edge back?
Thanks for the input guys![/QB]The shims go at the nose (front) of the Impeller on the shaft. Now when testing the Impeller on the shaft in the pump, add or remove shims to give .025-.030 clearance at the wear ring lip and Impeller front edge.
Now if by (slim chance) the nose of the Impeller hits the stop on the shaft...and there's to much gap at the wear ring lip and Impeller edge (this is without any shims)...then you'll have to machine down the Impeller nose. (rare)
Make sure the bushings in the bowl are new or in great shape...there actually teflon coated and should be grey in color. Check the Impeller to wear ring in several places to determin your final clearance.
Note...I would advise no less than the factory recomended clearence for (your) pump! Mine is at .018 but thats not recomended for a river boat!
[ November 08, 2002, 06:26 AM: Message edited by: HammerDown ]

[MikeF]

I get it wink . I'd want the same :cool: .
You are getting some quality information here! I do tend to agree w/ J123 on the hard anodizing. On one of the machines in the plant I used to work at we had some plain aluminum plates that wore out real quick. When we hard anodized them, there was no more wearing on the parts (that stuff is good!!). :)
Check those measurements that Jacuzer says to look at. He knows his stuff :) ! Schooled by the best :D
[ November 08, 2002, 08:06 AM: Message edited by: MikeF ]

[miller19j]

HD
I have new bearings and they are Teflon coated. I was planning at setting the clearance at .020 that is what the repair manual that I have says. But I was going to set it at a true .020 matched to my wear ring (witch is not its advertised diameter).
Jweeks123
I understand what you are saying but here is my problem.
My impeller has .005 runout and my bowl bearings feel like they have at least .003 clearance from the shaft (I have not actually measured them but will). I am installing all of these parts into two pieces that bolt together (tolerance unknown). And setting the clearance at .020 (.010 a side). Now if I add all that up I end up with the potential of .008 runout leaving only .002 for miss alignment of the bowl and suction piece before I end up with contact.
Thanks for all the input guys!

[Blown 472]

I think you might get into trouble running it tight, I had an imp get smoked because it had a piece of sand get caught between the imp and the wear ring, balled the alum up and then wore a groove in the imp, actually it was three grooves.
Have you talked to Jack at mpd bout this? great source of info.

[jacuzer]

In response to Hammerdown's last post
DON'T MACHINE THE NOSE OF AN IMPELLER!!!
(I'm not mad, just want to get the point across)
To close up the front clearance you machine the shaft.
Think of it this way, you run over a rock bar and destroy your impeller, you don't want to cut down the new imp so it will fit. You want to intall the new imp on the machined shaft, shim it if necessary and go. Also if you get into trying your buddies imp. he isn't going to let you cut it down is he?
PS. This is also why adding a stuffer to the bowl is much better than machining the front of the bowl down.
Kevin

[pops1]

[QUOTE]Originally posted by miller19j:
[qb]HD
I have new bearings and they are Teflon coated. I was planning at setting the clearance at .020 that is what the repair manual that I have says. But I was going to set it at a true .020 matched to my wear ring (witch is not its advertised diameter)
Trimming .005 is not a problem- You think all the Blueprinters re-Anodize Impellers after cutting Happens.-No! You might check for Balence on the impeller- Just a Hunch!
Good Advice Given above. Its Possable when the Impeller was CNC'd it built heat- Expanded and cooled in another configuration. If you are worried about the Anodize- E or Call Me and I will get it done for you on our next run of Impellers & check your Balance- N/C if you can wait. Dave
Jweeks123
[ November 08, 2002, 09:39 AM: Message edited by: pops1 ]

[miller19j]

I think that machining the shaft would be the best approach. It would also be easier to machine the shaft than the impeller.
This impeller is suppose to be balanced already, :rolleyes: But I am sure if it was not out of balance before machining it will be after I am done. I am not real worried about the anodizing I have several parts to go out to anodize (for work) and I will probably send this out with them.
What type of anodize do these things usually get? I am sending parts out for Mil-A-8625 Type II Class 2.
Thanks again for all the information. These boards have been very helpful!

[miller19j]

I just got my Impeller back from anodizing so that’s set. Thanks again for all your help guys!
I have one more question. What should the clearance between the front of the impeller and the suction piece be set to? I have been told to set it to .030 is that correct?
http://free.***boat.net/gallery/Gearhead_Garage/Motors_and_Drives/imp.JPG

[jacuzer]

Typical front clearance is .035 Min.
Make sure the impeller step(wear surface) is deeper than the wear ring & liner or else you will have to set your clearance between the impeller shoulder and the wear ring edge.(back side tolerance)
Hope this helps,
Kevin

[Jordy]

Dammit Miller, I can't belive you had it anodized black. Don't you realize how much that is going to slow you down, if nothing else just due to the drag created by the color? Chrome will get you home. :D

[miller19j]

Jucuzer,
Thanks I will check the back clearance. I think it is ok but I will check it again just to be safe.
Jordy,
I told them to anodize it Red I figured that would make me go faster but the shop did not listen to me! wink
RD,
I am not a Machinist but I get by with the Old School tools. I prefer the handles when Lathes and Mills have buttons on them I don’t know where to start. :D