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7x10, 7x12, 7x14 Mini-Lathe Information
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This is fast becoming
one of the more interesting areas of machining for me. When you first get
started, chucking a workpiece in a vise is all it takes to machine your part.
However, when you start getting into machining via CNC, it gets a bit more
complicated (and more interesting)...
We've broken this
section down further to include the following:
- Basic workholding (vises, blocks, clamps)
- CNC workholding (special jigs, fixtures, etc.)
- ER Collets (save your Z-axis travel)
- Mitee-Bite clamps (this company has some
interesting clamping methods)
- Phase 2 Quick Change Tool Post (QCTP) (this is
- Rotary Tables (make your mill function
like a lathe and more)
|er spring collets!
finally, after switching between r8 collets for endmills and the r8-shanked drill chuck and having 2"+ reduced in the
z-axis from the chuck itself, it was time to simplify things.
of the larger ranged er collets (32, 40) is that they have approx. 0.040"
flex range so you can easily chuck drill bits, endmills and whatever else round
shanked cutting tool in there.
the er32 set purchased from enco (accupro
brand) has a range between .078"-.787". below are some pictures. again,
after doing web searches for "er spring collets", "er
collets", "er32", etc... it was difficult to find information about these.
even manufacturers' websites had little basic info on this type of
so here's our attempt.
|here's the box from enco - it's an 18-piece er32 set
of accupro brand collets. it was in their hotdeals catalog for $230 which
is ~$12.77/collet. pretty good deal. these were made in taiwan.
a few other brands are ETM, bison, collis, hertel,
kennametal, valenite, erickson
these brands have collet chucks and spring
collets. there are different types of collets from the "traditional" r8 to
different types of spring collets (single angle, double angle, etc..).
there are different er sizes that basically
determined by their gripping range. for example, with er32, the full range
is between .078"-.787". while a smaller er16 ranges from .020"-.393".
a complete write-up will be posted sometime in the
near future. this was truly a confusing start.
|this is a r8 shanked collet holder. unfortunately,
enco (this one is model #dr-204-5005 from their hotdeals catalog) doesn't
sell r8 er32 collet chucks. this one was returned as it only works with
full-grip spring collets. not er type collets.
enco was great
about the return. i called them, spoke with a tech and sales rep, and
minutes later, a RMA number was issued and the collet was returned same
|enco didn't sell the r8 shanked er32 collet chuck, so
one option would have been to by a 1" straight shank er32 collet chuck and
chuck that into a 1" r8 collet. too complicated and increases the
potential for runout buildup. (sum of all runout)
mscdirect, travers, j&l, kbctools all sell various
forms of collet chucks, but j&l had the best price listed on their
website. j&l also sold import models of the r8 er32 collet chuck for under
$80. good deal but they were out.
the next price level up was the etm brand and
mscdirect was pricier at $165 for just the chuck.
you still need a special spanner wrench and theirs was $20.
so a call to j&l and the sales guy basically was
great about pitching me the right products - not too pushy (i even tried
to see if they would import a super x3 mill from
they didn't have the import model in stock (would
arrive in july) but he sold me the etm for $109! sounded good. added a $10
spanner wrench and was good to go.
apparently, etm is an israel-made product.
|really nice quality.
i was concerned about losing upwards of 2" of
z-axis travel due to the nut, but this was not the case.
|here's s #10 machine screw drill bit mounted. i no
longer need to use the drill chuck!
|here's the spanner wrench.
|here's an interesting note. see the diamond-shaped
engraving on the top of the inner shiny circle? not sure if this was done
on purpose, but this is where you insert and eject the collet.
|this picture shows the inside. there's a retaining
clip with two ears at the bottom. you start clipping in the collet here
and push down at the top to seat the collet. ejection is the reverse.
|here's an inside view of the r8 er32 with the spring
recap: with a
total cost of:
$110 - r8 er32 collet chuck
$10 - spanner wrench
$230 - full set of er32 spring collets
TOTAL = $350
it wasn't cheap, but it was cheaper than any set
you can buy out there. many of the sets do not come with a full range of
collets. for example, at msc, you can buy their etm brand set and it comes
with the r8 chuck, spanner wrench, case, and only 11 collets for a
whopping $495! if you were to add the remaining collets to make a full set
(at $13/collet) the total would come to $495 + [(18-11)*13] = $586.
so by buying bits and pieces, you can save $236!
the advantage of using these is that between bit
changes from endmills and other cutters to drill bits, you no longer need
to swap out the r8 collet each time. plus, the additional z-axis travel
you get by not using a drill chuck is nice.
the only disadvantage is that you have to unscrew
the nut off the chuck each time, but may end up still saving tooling
quick notes (a full FAQ is
being written up):
common er spring collet
- ER-16 (major dia. of collet 0.670" - gripping
range of 0.020"-0.393")
- ER-20 (major dia. of collet 1.230" - gripping
range of 0.040"-0.511")
- ER-25 (major dia. of collet 1.390" - gripping
range of 0.040"-0.629")
- ER-32 (major dia. of collet 1.300" - gripping
range of 0.080"-0.787")
- ER-40 (major dia. of collet 1.620" - gripping
range of 0.120"-1.020")
collets from different ranges are NOT
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