Anyone have collets die early?

[knight_toolworks]

my collet I got from msc (their medium priced one) I got one bit out of it maybe 4 hours runtime. I put in a new bit and it slipped. tried another one and the same thing. I checked the shaft size and it was right.
where I got about 18 hours out of my 1/2" collect I bought locally. this is running 1/2" bits with a 2" cut and they tend to stress collets more.

[elcruisr]

Don't try to save money on collets. They don't last! I speak from hard experience......

Always buy high precision collets. I buy mine from my local Onsrud tool dealer and they are Techniks brand. I get anywhere from 300 to 400 hours of usage out of them. The worst I've ever had with them was some really high vibration jobs with 1/2" tools and it lasted 150 hours.

[elcruisr]

One more thing to check is the torque on the cap nut. With my collets they spec 85 foot lbs. To high or low on torque will significantly lower their life span.

[ed_lang]

So how do I check the torque on the nut? I have several torque wrenches but not a wrench that will fit where a 1/4", 3/8" or 1/2" socket would and the nut too.

[Brady Watson]

http://techniksusa.com/metal/torque.htm

-B

[elcruisr]

That's the torque wrench I'm using. Very good one as well.

[knight_toolworks]

I have been buying collets in the 25.00 range. though this last 1/2" one was a 15.00 as it was all I could find.
so it sounds like it may be an over or under tightening issue.
so how much did that puppy cost?

[knight_toolworks]

man that torque wrench is spendy 240.00 and another 27.00 for the wrench end.

[Brady Watson]

Yeah, but you only have to buy it once...and it will extend the life of your collets, so in the long run, it becomes free.

-B

[knight_toolworks]

well ya but tell my wallet that right now (G)been broke for awhile and finally making some money but also playing catchup on the bills.
what size is the wrench for the spindle? I found an interchangeable head wrench that would work for about 170.00 total.

[Brady Watson]

Depends on the spindle - an HSD 4hp or Colombo 5hp use the 'Big E' ER25 wrench.

Post up your link for the cheaper wrench. I'm sure others will be interested in seeing a cheaper alternative.

-B

[knight_toolworks]

n ot as cheap as I thought I was looking at the wrench for 150 inch pounds not foot. to go to foot the wrench is 179 and the 27 mm open end wrench is 61.00 from msc so you only save about 50.00

[ed_lang]

Brady sure does know how to spend the extra money I don't have!

I think the wrench will have to be on my list of items to get.

I will keep checking my mail each day and see if anyone sends me one!

[Brady Watson]

Check your email often...miracles happen every day if you're open to it


-B

[harryball]

I know the feeling Ed, all the pretty toys and either no money to get them or time to use them if you did.

Sometimes I feel... if my ship came in and the pier was still standing the gang plank would land on me. Other days I think I should just swim for it. And on others still, life seems a beautiful woven tapestry that turns out just right.

As for my email, I check it often. All I need is a few crackers and cheese to go with all the SPAM. No torque wrenches here! :-)

I've never worried about the torque (until now, thanks guys ;-) I make sure it's tight consistently with the same hand. I figure if it is as tight as I can squeeze and it holds this time, it'll hold next time. Never had any slippage.

Robert

[elcruisr]

OK, now the bad news.......

Overtightening a collet can introduce additional runout on the tool and vibration. That means shorter bearing and tool life. It can actually twist the collet slightly in the holder. Not the end of the world for lightly used machines but it becomes an issue if you stand over your 'bot with a cat 'o nine tails like I do!

[mzettl]

Couldn't one adapt a collet wrench to use with a normal torque wrench? It would involve cutting a 1/2 inch square hole in the collet wrench to accept a 1/2 drive torque wrench. You would then have to calculate a factor to use as a multiplier to compensate for the increased moment arm. Seems like it would be fairly simple to do, and would be a far less expensive alternative than buying a single purpose $250.00 torque wrench.

-Matt

[sailfl]

Matt, Interesting that you had the thought of a torque wrench / collet wrench idea. I was searching for some thing else and came across this:

http://techniksusa.com/metal/torque.htm

Just what you were thinking of.

[john_l]

Matt, I notice that on the Technikusa web page that the pictures of the interchangeable wrench heads, for the various collets, seems like they will be varying lengths when used.

Is this what you meant by calculating a multiplying factor for the increased moment arm?

I'm no engineer so I probably can't handle the science... but I wonder if you know why a factor would be required for a modified torque wrench and not the Technikusa tool at it's different lengths?

Thanks, John

[john_l]

... and email isn't all bad. I am actually currently awaiting my cut on a fund transfer from a wealthy Nigerian foreign ministry. Things will be looking good around here real soon.

[ed_lang]

I think I see my ship on the horizon!

Now where did I put that rope? I am not going to let this one pass by.

Thanks

[mzettl]

John,

I noticed that about the various heads on the Technikusa website as well. My suspicion is that the change in the length of the moment arms with these various heads is small enough that the resultant difference in the force required to produce the same torque is not enought to worry about.

The math is actually quite simple. Torque = Force x Length of Moment Arm. So, the force required to procuce a given torque is directly proportional to the length of the moment arm (the distance between the center of rotation and the point of application of the force). What you would need to do is measure the distance between the center of the square drive on the torque wrench and the center of the handle, as that is where the force is more or less directed. We'll call that distance "x." If you then add the collet wrench to the end, and extend the length of the moment arm by lets say 2", you now have a moment arm of (x + 2). The proportion, x/(x + 2), would be the factor you would multiply times the original force, in this case apparently 85 ft. lbs. As you can see, the force required will be smaller because of the longer lever arm.

I hope that made sense.

-Matt

[harryball]

If you make your own all you need to do is keep the wrench at a right angle to the extension, the torque reading will be reasonably accurate provided you are very close to a 90 degree angle.

That said... you could easily modify a collet wrench to include a socket hole in it then use a beam wrench or dial wrench (no storage issues leaving them set like a click wrench) then just place the wrench in the socket hole so it is at a right angle and torque the nut to the desired setting. No math required.

Robert

[mzettl]

Robert,

You're correct as long as you place the socket hole in the collet wrench close to its center of rotation. It would be like adding a crows foot wrench to the end of the torque wrench. In that case, by putting the torque wrench at a right angle to the collet wrench, you would not be changing the moment arm by very much, and could use the same setting.

However, if you put the socket hole out at the very end of the collet wrench, then the moment arm would be quite different even at the 90 degree angle.

Your method is certainly easier, and there would be no reason to not place the socket hole close to the business end of the collet wrench. Good tip!!

-Matt

[knight_toolworks]

well got the torque wrench today and the 27mm wrench. the wrench was way to thick and I had to grind about 1/2 off the thickness. but now I know where I have gone wrong. not tight enough by a fair amount. it really takes some beef to get to 85# myself it would be hard to over tighten I would think. this setup saves about 75.00 buying from msc over the other recommended brand. myself I am glad I got the wrench I think it would be hard to use this on the nut.


7020

7021

[knight_toolworks]

Of course the crowfoot idea is a good one but I just checked and could not find a 27mm wrench the largest was 23mm I think.

[paco]

quote:man that torque wrench is spendy 240.00 and another 27.00 for the wrench end
Steve, where did you get that price?! Our dollars are almost equal but I'm quote $300 for the wrench and $36 for the wrench key (ER slotted). That's from a local Techniks reseller.

Out of curiosity, just how many of you Botter use such a wrench to correctly load the collet?

[knight_toolworks]

the price was from a local dealer.