504,500 active members
3,530 visitors online
Register for free
Login
Results 1 to 8 of 8
  1. #1
    Registered
    Join Date
    Nov 2017
    Posts
    457

    Buying stock for 5c collets

    I'm running into an issue when buying stock. Most of it is at least a few thou oversized, sometimes more. I can jam it in there if I really force it, but there's no way my bar puller is gonna be able to handle that. This is mostly aluminum bars, some brass. How are you guys dealing with this? Are certain suppliers better about on size or slightly under size stock? I would think going a 64th up in size on the collet may work, but it can't be optimal since it's only gonna grip at the nose. Only other option I can think of is turning some emergency collets like 5 thou over my common stock sizes, but I thought I would check and see how others are dealing with this

  2. #2

    Re: Buying stock for 5c collets

    I've had the same oversize problem, I actually had to grind a couple of my 16C collets to fit the material we are getting, ~1.505 and ~1.230. We did get some precision aluminum stock in one order that was on size, but if you ordered that as precision stock I suspect it would be expensive. The last batch of 1 1/4 that we got measured at around 1.249. We buy from a large vendor, but we are buying by price rather than precision.

    Hardinge will make collets in any size you want....... for a price $$$$ They might stock some over size collets.

    Using emergency collets might be the best option.
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
    Registered
    Join Date
    Jun 2005
    Posts
    230

    Re: Buying stock for 5c collets

    In my opinion Service center brand aluminum is the worst I have lot of bars oversize I can't use.
    The chips don't break very well to gummy ,I avoid it like the plague.

    I have always used Alcoa bought out by Sapa and then bought out again and now called Hydro.
    I have NEVER in 30 years had a bar not fit in a collet, Chips breakup very well I always specify Hydo when ordering
    material .
    Tim

  4. #4
    Registered
    Join Date
    Feb 2011
    Posts
    248

    Re: Buying stock for 5c collets

    with aluminum material there is extruded and cold drawn
    the extruded has a lot more tolerance to the spec's then the cold drawn
    cold drawn 0-.500 is +/-.0015
    .501-1.000 is +/-.002
    1.001-1.500is +/-.0025
    1.501-2.000 is -/*.004
    extruded starts at 0-.125 dia. at +/-.006and goes up from there
    there is a price difference between them though the extruded is cheaper

  5. #5
    Registered
    Join Date
    Nov 2017
    Posts
    457

    Re: Buying stock for 5c collets

    So I was thinking i would just start buying cold drawn for better tolerance, but what downside would there be to just buying emergency collets and boring to fit the cheaper stock? I can get cheap import emergency collets for 8 bucks. Obviously runout doesn't matter since I'm boring them. Possibly even better runout than a sized collet since it will be loaded in the spindle the same way while it's being bored as it will be while being used for holding since I use the index pin. As for the reduced hardness, I only run aluminum and brass so that shouldn't really be a downside either right? Even cold drawn stock isnt always gonna be a perfect fit in a sized collet. I really want a perfect low resistance slip fit so my bar puller can be reliable and boring my own collet will allow me to really fine tune that.

    What would be the downsides to going this route? I haven't bored any emergency collets yet, is it harder than I think to bore a nice concentric low runout collet?

  6. #6

    Re: Buying stock for 5c collets

    Quote Originally Posted by QuinnSjoblom View Post

    What would be the downsides to going this route? I haven't bored any emergency collets yet, is it harder than I think to bore a nice concentric low runout collet?
    There really isn't any downside. No problem boring your own, the ones I have done machine very nicely. One note, the only time a collet (or chuck for that matter) needs to be perfectly concentric is when re-chucking a part that is partly done and needs a second op. When cutting raw material, the part will always be concentric to the spindle center of rotation. Even the stock is not going to be perfectly round unless you are buying TG&P stock, and even then it has a roundness tolerance.
    Jim Dawson
    Sandy, Oregon, USA

  7. #7
    Registered
    Join Date
    Nov 2017
    Posts
    457
    Quote Originally Posted by Jim Dawson View Post
    There really isn't any downside. No problem boring your own, the ones I have done machine very nicely. One note, the only time a collet (or chuck for that matter) needs to be perfectly concentric is when re-chucking a part that is partly done and needs a second op. When cutting raw material, the part will always be concentric to the spindle center of rotation. Even the stock is not going to be perfectly round unless you are buying TG&P stock, and even then it has a roundness tolerance.
    Yep, true. I guess I'm also thinking about emergencies for second op stuff. I'll try boring one and see how it goes.

    On a side note, I got some 135 split points as you recommended in my other thread. I got a solid carbide 1/4, 3/8, and 1/2. Since I now have the alarm wired for my horizontal servo spindle, I wasn't afraid to just go for it. If servo spindle faults, machine stops. Anyway, I chucked up the 1/2" in one of my boring/drilling gang tool slots (er20 holder), loaded up a 1" bar of 7075 and set up to drill at 2400rpm and 20 ipm (about 300sfm and 8 thou per rev). It plowed through that 7075 like butter. Barely even sounded like it was cutting.
    Very happy with this mill turn setup so far. Videos coming soon, just want to get the bar puller operational first So i can show the full capability. Ill update my original mill turn thread from when I first started thinking about this project. Building the new control cabinet this weekend to better organize all the new I/O.

  8. #8

    Re: Buying stock for 5c collets

    Looking forward to the videos
    Jim Dawson
    Sandy, Oregon, USA

Similar Threads

  1. Replies: 0
    Last Post: 04-13-2018, 09:43 PM
  2. Replies: 3
    Last Post: 06-17-2016, 04:55 PM
  3. Buying stock from Onlinematals.com
    By FoxCNC1 in forum General Material Machining Solutions
    Replies: 4
    Last Post: 08-09-2015, 01:02 AM
  4. Buying metal stock in NJ
    By maly-miller in forum General Metalwork Discussion
    Replies: 0
    Last Post: 03-12-2014, 05:00 PM
  5. Buying aluminum stock, flatness issue?
    By mamexp in forum DIY CNC Router Table Machines
    Replies: 7
    Last Post: 12-22-2011, 02:00 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •