Poor fit of prop to stub shaft. Video included. .007"of slop, is this normal?

[Snowboard_Nut]

http://youtu.be/ZU61XhCPac4

Brand new Revolt. Took the prop off to sharpen and balance before the initial run. Right away I notice horrible slop in the fit of the Grim Racer prop to the stock shaft. I am a machinist by trade, and so of course I immediately start taking measurements and discover a .007" of slop in the fit. The prop's ID measure's .191", and the stub shaft measures .184"... The inside of the prop ID looks rough, almost gaulded as though the drill bit was not oiled as it was drilled. So, in regards to both the prop and the shaft, is this level of inprecision to be expected? I would think the stub shaft would be made of stainless center-less ground material resulting in a perfect 3/16"(.1875")...

[Cooper]

You are right but unfortunately chinglish measurements equal a 3/16 shaft and inner diameter hub of .187. Tighten the hub nut and your good to go.

[Snowboard_Nut]

Thanks Cooper. If I were to buy an Upgrade Cable Assembly from Kintec that claims it's made in the USA, I should get a true .1875" stub shaft, correct? And as far as the prop, is Octura made in the USA? Are they more precise and better QC than Grim Racer props?

[martin]

Most good quality after market stubs that I use or including ones I make measure .187"- .1875", my Octura props measure .188".

[martin]

I have heard that ABC make Grimracer props which is a good prop manufacturer in the USA, ive just measured some of my ABC prop bores & they are also .191" - .1915". They have an acceptable fit on my .187" stubs but I understand how much looser it is on a .184" stub.

[Mike Caruso]

http://youtu.be/ZU61XhCPac4

Brand new Revolt. Took the prop off to sharpen and balance before the initial run. Right away I notice horrible slop in the fit of the Grim Racer prop to the stock shaft. I am a machinist by trade, and so of course I immediately start taking measurements and discover a .007" of slop in the fit. The prop's ID measure's .191", and the stub shaft measures .184"... The inside of the prop ID looks rough, almost gaulded as though the drill bit was not oiled as it was drilled. So, in regards to both the prop and the shaft, is this level of inprecision to be expected? I would think the stub shaft would be made of stainless center-less ground material resulting in a perfect 3/16"(.1875")...

Correct on all points. Grim props run well but first you have to fix the mounting hole so you can balance it right. With your whole machine shop you could bore the prop out and press in a sleeve done deal. At home most of us guys have to use JB Weld and a tooth pick to fill the low spots and ream after words will also get you to where you can balance it with a fairly good fit. 45X68 runs 48 mph on my stock powered revolt. Longer run time with the smaller std prop that comes with the boat.
Before you run the boat replace the Collet, Cable and add front and rear thin wood to the battery tray and it will last like mine even holding the Grim 4s battery.
It is a great boat for $$$ spent and will do u turns at 40 mph like you cannot believe. .150 drive cable not made for big props and Drag race starts. I run Hughey and Octura cables with Teflon liner BUT the reson mine does not walk up the tube is I add a very short piece of hose between the (cable nut) collet and stuffing box tube. If you change collets just trim off what you need from the end of the stuffing box tube.
Good luck.
Mike

[Mike Caruso]

Oh ya cut off those Deans wire connectors and install something with 5.5 bullets there are nice ones out there that are polarized makes life easy. The ones on the motor to the ESC are fine just keep them clean with DeoxIT D5. Buy some Corrosion-X for RX just open it up squirt it all over the board inside, inside the motor. Then relube motor bearings just some good Syn lube I like SIN Lube from ACER Racing.
Oh and by all means buy a tube of Shoe Goo and take ever screw out of the transom seal the threads and then check it in the bath tub. Shoe Goo fixes everything at the pond LOL.

[photohoward1]

[QUOTE=At home most of us guys have to use JB Weld and a tooth pick to fill the low spots and ream after words will also get you to where you can balance it with a fairly good fit.[/QUOTE]

I have never heard of this? Been running 25 years. Just balance and tighten the nut. You guys are way being way to anal on the sizes.

[Snowboard_Nut]

Most good quality after market stubs that I use or including ones I make measure .187"- .1875", my Octura props measure .188".

Are your shafts and stubs available in the US? Are you using cold-rolled steel bar, or center-less ground high precision stock? stainless or steel? Have a website?

[Snowboard_Nut]

I met with one of my club buddies today for a little test session at our club lake. He brought his new Revolt with him just so I could take measurements. He already had the prop taken off and onto another boat but I did get to measure his stock stub shaft and his was even worse at .182" !!! yikes! not impressed! and based on a previous comment on this thread is seems Grim Racer Props are running pretty consistent at .191" so he probably has .009" of play.... This seems unacceptable after reading so much about how a perfectly tuned prop makes so much difference, what's the point if the prop won't run concentric because of it's mounting scheme?

[Snowboard_Nut]

You guys are way being way to anal on the sizes.

Personally speaking, I disagree, perhaps it's the machinist in me.....

[Snowboard_Nut]

Correct on all points. Grim props run well but first you have to fix the mounting hole so you can balance it right. With your whole machine shop you could bore the prop out and press in a sleeve done deal. At home most of us guys have to use JB Weld and a tooth pick to fill the low spots and ream after words will also get you to where you can balance it with a fairly good fit. 45X68 runs 48 mph on my stock powered revolt. Longer run time with the smaller std prop that comes with the boat.
Before you run the boat replace the Collet, Cable and add front and rear thin wood to the battery tray and it will last like mine even holding the Grim 4s battery.
It is a great boat for $$$ spent and will do u turns at 40 mph like you cannot believe. .150 drive cable not made for big props and Drag race starts. I run Hughey and Octura cables with Teflon liner BUT the reson mine does not walk up the tube is I add a very short piece of hose between the (cable nut) collet and stuffing box tube. If you change collets just trim off what you need from the end of the stuffing box tube.
Good luck.
Mike

I had thought about a sintered bronze bushing sleeve, but an accurate holding fixture could get very complex due to mold flash and other imperfections on the hub surface, and it may only work on one size of prop if it relied on blade position. I am going to try some .003" shim stock and roll it into a "C" shape with no overlap at the ends and then attempt to slide that inbetween the prop and stub shaft. What is it about the collet that you dislike? Only 1 setscrew? Or the jaw design of the collet? How many jaws are in it, versus a upgrade like Kintec? I really don't like the idea of cutting the stuffing tube, I prefer to have the end of the tube as high as possible for peace of mind of water entering more easily if the boat stalled and took along time to be able to get to. I understand the benefit of an upgrade flex, as in the larger diameter wire being used, but is the stock flex soldered at the ends, or welded? It seems I see a lot of talk of upgrade flex's being welded ends. And i'm having a hard time understanding the tubing between the collet nut and the stuffing tube you mentioned, is this to prevent water "walking up" the flex like an Archimedes Screw, or are you saying this relieves the contraction of the flex cable under load? Do you have a picture of that?

[Snowboard_Nut]

Oh ya cut off those Deans wire connectors and install something with 5.5 bullets there are nice ones out there that are polarized makes life easy. The ones on the motor to the ESC are fine just keep them clean with DeoxIT D5. Buy some Corrosion-X for RX just open it up squirt it all over the board inside, inside the motor. Then relube motor bearings just some good Syn lube I like SIN Lube from ACER Racing.
Oh and by all means buy a tube of Shoe Goo and take ever screw out of the transom seal the threads and then check it in the bath tub. Shoe Goo fixes everything at the pond LOL.

Yeah the Dean's will be the first to go. I am going to run the red cased 5mm polarized bullets that come on the Nano-Tech 4s 5k mah. As far as the Rx, I coated it in 3M Skotchweld DP270 Potting Compound, AWESOME stuff! I was able to keep access to my failsafe button and LED, and I coat all contacts with dielectric silicone grease :rockon2: And I use Tri-Flow for all my motor bearings. I like the fact that it appears the motor has screws on the endbell so down the road it looks like we can replace bearings when needed. As far as transom leaks, I was leaning towards Plumbers Putty?

[Doby]

Pretty sure those red connectors are only 4mm, not 5mm....I used those in the past as well and they quite often "fused" together from the heat...go to 5.5 bullets.

[Snowboard_Nut]

Pretty sure those red connectors are only 4mm, not 5mm....I used those in the past as well and they quite often "fused" together from the heat...go to 5.5 bullets.

Yup, they are 4mm. Oooops. Our club is buying 7 of these boats for club racing and we are going to use the stock props, stock motor, and stock esc. Think the 4mm will be OK under those circumstances? (I just ordered a bunch of the bare 4mm with sleeves). Our racing will be 6 laps.

[tlandauer]

I am using a grim Racer 40x52/3 prop on an OSE shaft, I have to push quite hard for it to slide up to the drive dog. May be just sloppy production, and I know how frustrating it is to you. Regardless of which way you are going to go, buy an up grade cable/shaft. I believe you will be much happier! Never any problem with OSE up grade item. AC stock shaft is an item you need to replace ASAP anyway. Let's just leave it like that, no bashing brands.

[Mike Caruso]

I had thought about a sintered bronze bushing sleeve, but an accurate holding fixture could get very complex due to mold flash and other imperfections on the hub surface, and it may only work on one size of prop if it relied on blade position. I am going to try some .003" shim stock and roll it into a "C" shape with no overlap at the ends and then attempt to slide that inbetween the prop and stub shaft. What is it about the collet that you dislike? Only 1 setscrew? Or the jaw design of the collet? How many jaws are in it, versus a upgrade like Kintec? I really don't like the idea of cutting the stuffing tube, I prefer to have the end of the tube as high as possible for peace of mind of water entering more easily if the boat stalled and took along time to be able to get to. I understand the benefit of an upgrade flex, as in the larger diameter wire being used, but is the stock flex soldered at the ends, or welded? It seems I see a lot of talk of upgrade flex's being welded ends. And i'm having a hard time understanding the tubing between the collet nut and the stuffing tube you mentioned, is this to prevent water "walking up" the flex like an Archimedes Screw, or are you saying this relieves the contraction of the flex cable under load? Do you have a picture of that?

Collet single screw no problem it's on the cable end. The AQ first collect had three fingers that held the cable they broke too brittle heat treat. The second style has four fingers seems much better. Brass tubing 1st make sure you cannot move it by twisting. If you can just pull it out ruff with 80 grit and reinstall with Shoe Goo I added a support with wood and West Systems Epoxy. Distance between the collet and brass tube on mine is maybe 1/4 I fill that space with fuel or water hose that just slips over the cable. it will also just barely rub on the Teflon liner which help keep the water from coming up the cable in to the boat. I run a .150" cable in my boat. I solder my stub shafts onto the cable. I takes prep work on the cable to get all the oil out of it before you tin the ends. Yes tin the end that goes into the collet too.
All my pictures are in the Gallery just do a search from Mike Caruso. If you look close you will see I also added thin wood the the front and back of the motor mount blocks too. My boat has been trouble free because I did all the upgrades before it hit the water for the first time. 40 years in RC boating has taught me not to rush things.

[Cooper]

:rockon2:I know you are experienced in quality tolerances but NO drive line is balanced. In my opinion it is a must to at least balance props. You really don't have to but an unbalanced prop will just speed up the process of wearing things out.
1 impossible to balance a flex shaft
2 drive dog can only be balanced if you permanently attach, as any adjustment to set screw unbalances it
3 retainer-nut or bullet, both ways need to be balanced
4 bushing inside stinger will not wear evenly
5 impractical to be using bearings and would need needle bearing if used
6 collets aren't balanced, some better but will be spending $40+ for one.
7 any gap in Teflon/tube/flex will oscillate resulting in imbalance
8 even if all these were perfect a good coating of grease throws it all off.

That's the reality of it. Now I'm not saying those things can't be done but at what level are you willing to take it to? I have some setups that I'm running over 50k rpm (saw only) and I do take great measures attempting to balance as much as personally possible to lessen imbalances. But it is just a necessary evil we can only minimize but not eliminate. But you are on the right track and in my opinion a balanced prop in a necessity. I have a pursuit that I just plug and play, even run damaged props, and at end of season I might have to replace the bushings. Opposite side of that I ran my saw cat knowing the prop had a very slight nick it it and that resulted in the stinger being torn off, broken shaft and lost that prop that had a lot of work into it. One of those things I kicked myself in the but for because I knew I should have repaired it, not one more run it. Lol,,,,, I think the welded flexes from kintec are great, sometimes a little sanding is needed. But to me it sounds like you just got a sloppy prop, I don't think that is common, but as others said some things to combat the loose tolerances. Good luck and you are willing to do way more that most do, as it's only going to be a benefit

[Snowboard_Nut]

I am using a grim Racer 40x52/3 prop on an OSE...

what kind of speeds are you getting? whats your battery?

I agree, No Bashing, just recommendations from other experienced and HAPPY pilots of this wonderful boat....

[Cooper]

:smile:these are all from kintec, some new and some used. Welded shafts, ground, pretty good in my opinion. More pics but you get the point, I think only one was 187, all others were 1875, even the lightly used ones.

[tlandauer]

what kind of speeds are you getting? whats your battery?

I agree, No Bashing, just recommendations from other experienced and HAPPY pilots of this wonderful boat....

I am so so sorry, I meant my prop fits well on an OSE shaft. I use that prop for my BBY Zephyr Hydro. Sorry to confuse you, man. Anyway, as I said, it really is a tight fit, of course I did not measure, I am not a machinist by trade, but I understand your frustration.

here is my last run on that hydro:https://www.youtube.com/watch?v=uzLh_xD0k1U
Not that it's that impressive speed wise, but hey, I am happy with even little progress on my part setting up the boat.
:beerchug:

[Snowboard_Nut]

:smile:these are all from kintec, some new and some used. Welded shafts, ground, pretty good in my opinion. More pics but you get the point, I think only one was 187, all others were 1875, even the lightly used ones.

That convinced me. I ordered a Kintec.

[Cooper]

And this is why I love the forums, you got me thinking about tolerances so I thought I would check. I make my own and this discussion got me thinking about a problem I was having, the shaft had bent and was causing problems. I just didn't think about checking but reading this gave me new perspective to my problem. So thanks for the post and keep the questions coming. :)