MBP Collet Orientation against Flat Spot on Shaft

[tlandauer]

As the title says, these high quality German collet is nice but it seems that they were engineered with a round/non-flattened shaft in mind. Should I be extra aware to position the clamp so the two halves are not "parallel" with the flat spot? Seems that this will allow the clamp to grab the majority of the motor shaft.
On RocketCitying racing it says if the flat spot is within 15% of the shaft , it will be ok, another words for a 5mm shaft if one uses a caliper to measure from the flat spot, it should not be less than 4.4mm.

http://rocketcityracing.com/cart.php?target=product&product_id=208&category_id=245

[Rocstar]

How MPB says to use them...

The degree of the flattened surface must not exceed 15% (0,6 mm) of the shaft diameter
skizze.jpg

[tlandauer]

How MPB says to use them...

The degree of the flattened surface must not exceed 15% (0,6 mm) of the shaft diameter
[ATTACH=CONFIG]120856[/ATTACH]

Thanks so much, glad I asked, I am dead wrong on my instinct!

Oh Boy, haven't done one thing correctly this week, lol......

Sent from my Droid using Tapatalk 2

[ray schrauwen]

Is it a must to have the whole 15mm length of motor shaft for these collets??

[olwarbirds]

Ray I've been using them on almost all mine and my buddies boats and I havnt found that to be necessary. They do seriously grip...now if I can just get my order of them from Rocketcity to fill almost month old B/O....DJ

[tlandauer]

Hi DJ,
I just got to their site, it seems they have a new "beefier" style, I bought mine used, but in good condition, this is the first time i am using it and how tightly must one turn the nut to tighten the cable, it is aluminum and I am a bit worried since i am used to the brute force with which one must use for either the Octura and the cheap Chinese made ones.

[grsboats]

Don't worry about hard tightening the nut..it is a high grade product and you will see the difference in your equipment.Gill

[olwarbirds]

Yeah just snug it up, excellent products from MBP. I'm sure you will be impressed....DJ

[tlandauer]

Don't worry about hard tightening the nut..it is a high grade product and you will see the difference in your equipment.Gill

Thanks, Gill, that is good to know!

Yeah just snug it up, excellent products from MBP. I'm sure you will be impressed....DJ

Yeah, it looks and feels great ! I always thought only the Chinese ones would fail but today an Octura did that on me , I thought they were strong and I tighten them quite well. Also it is worth mentioning that on these steel collets I use anti-seize compound so metal-to-metal galling is not the issue and the grease does a good job of allowing the nut to go further down the thread. After the failure I took a new one out of the bag and that one is DOA! ( severe machining problem, can't turn more than 1/4 of the way )
I think it is time to up grade.

[ray schrauwen]

Yep, most of my chinese couplers are toast. Some I just won't use because they are so 'out'. The short Octuras aren't bad and yes to anti-seize, it helps a lot. I've been put off by price of MBP but, I might break down an try some. Other than those H&M make very nice couplers too but, by the time you get it they would cost same as MBP.

[iridebikes247]

They're good but its a good idea to solder the end of the flex. This is done to prevent the cable from twisting or compressing when tightening the nut, the collet is aluminum and the aluminum is thin on the 1/4" ones.

I have spoken with Jochen and 15mm is the minimum when securing to the motor shaft, you could probably get away with 14mm insertion depth but anything more I rec. recessing your motor mount or whatever you need to do to get it to this depth.

---Also if the flex is soldered on the end the nut will tighten up very quickly, so you won't feel the need to really tighten it down, I have had about 8 of those collets and never had a problem stripping out the nut. I did though, receive a collet from mbp and the 3mm screw was stripped and had to be re tapped for 6-32s.

[tlandauer]

It never occurred to me that the soldered end of flex would prevent compression. I always thought it is to prevent the strands to go unravel. I am sure this has been covered before, but what is the best way to put solder on the end? Is there a special flux and solder for steel wires?

[iridebikes247]

Didn't really occur to me either until I started buying gundert flex cable from gundert.de. Best 1/4" flex around its much quieter than some of the other stuff out there. Anyway There are a ton of strands and its impossible to push into a collet. On thicker cable I used retaining glue but I don't think this would work as well on the gundert stuff.

Anyway I went through a lot of solder trying to do it, very hard to solder these things. One prep trick would be to dunk the end of the flex in acetone for a day or two to get any grease off then scuff with sandpaper. As far as the actual soldering goes I couldn't get it to stick despite many efforts so had a friend help me do it.

I'll see if he can post some advice on how to solder them later today. I never ran soldered flexes really and you notice over time the collet doesn't loosen at all on the cable and everything just fits better. I gave the advice but needed help doing it lol

[ray schrauwen]

I like using a silver solder with acid flux. It comes as a kit Staybright Solder. There are other types as well.

[tlandauer]

Thanks guys, I will look into that. My cable is a .187 Aeromarine and the strands are thick and hard, but I think when the Octura let go it just may very well be that the cable was somewhat compressed/deformed and although I thought I had tightened it quite securely, the unaccounted for change under the pressure of the collet contributed to the failure.
Learn something new everyday!