Discussion Topic |
|
This thread has been locked |
| Messages 1 - 12 of total 12 in this topic |
Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
|
|
|
Topic Author's Original Post - Sep 13, 2010 - 04:59pm PT
|
I think pretty much all drill holders used to be the Rawl type. Rawl doesn’t make them any more but they were pretty simple; a length of hex (tool?) steel with a tapered hole in one end, a cross drilled through hole for a little wedge key to knock out the bit and remove it from the handle. (Was the Fish drill just a Rawl?)
My guess is that a couple things happened that made the Rawl type drill holder obsolete. First, in 1975, Bosch came up with the SDS chuck (Special Direct System) which used a cylindrical shaft with slots rather than a taper and became the most common type. Second, battery powered tools became powerful enough to provide a portable hammer drill and the SDS became the standard shank.
Nowadays, about the only people on the planet using hand drills are climbers and all the holders seem to have switched to the SDS drill shafts. The holders either use a set screw or collets or some such thing to hold the drill shaft. They all seem to have become pretty expensive for something that simply holds onto a drill so you can pound on it.
If I recall correctly, some people claim SDS bits are better but this doesn’t make sense to me since the design of the shaft that fits the chuck doesn’t have much to do the drilling parts like the carbide tips and the twist grooves. It seems to me that you could put a good tip a drill with any type of chuck shank.
Perhaps the loose fit of the SDS type shanks result in fewer broken bits or bits stuck in the rock. I would guess the taper bits get stuck in the handle too.
I’ve never used a Rawl holder but I do have an old Skil roto-hammer that uses A-Taper bits and I’ve never had trouble with it. A and B taper bits are still available (just Google “A Taper masonry drill bit”). I’ve read somewhere that some climbers prefer the old Rawl holders. They also seem like they would be fairly cheap to make.
So, anyway, anybody have any opinions about taper bit drill holders? Do they work? Do they break bits? Do bits get stuck in the rock or the holder?
I am in the process of producing a cheapo, home-made, dirt-bag, A-Taper, drill holder and will let you know if it is a success. I’ve ordered some 3/8” bits
Also, any qualified opinions about grade of steel and/or heat treatment? Seems like you wouldn’t want it very hard.
One more question, has anybody tried sharpening drills with a diamond grit stone, file or ginder?
|
|
TGT
Social climber
So Cal
|
|
|
Sep 13, 2010 - 05:29pm PT
|
Morse A taper reamers should be available from a machinists tooling supply house as well as the correct pilot hole bit.
I've machined larger Morse tapers with a boring bar in a lathe, but the A size is just too small to do that with.
Just drill out the center of a piece of hex stock in a lathe, ream in the taper, then mill the slot for the removal wedge.
Probably cheaper and easier to buy an A taper adapter for a rotohammer and machine it down to the length and diameter you want.
Green carbide wheels work for carbide bits. No need to go to a diamond wheel.
|
|
Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
|
|
|
Topic Author's Reply - Sep 13, 2010 - 07:00pm PT
|
I've measured an A Taper shank and it seems to be the same dimensions as a Morse Taper 0 (MT0) but without the tang at the end. I haven't found a reference to verify that.
I have an adaptor and plan to try it but have my doubts about how well it will hold up to endless pounding.
|
|
Oxymoron
Big Wall climber
total Disarray
|
|
|
Sep 13, 2010 - 07:00pm PT
|
I just use High speed steel bits. Ask B Law about those.
Rawl holder. I'm a dinosaur. Rawr!
|
|
adatesman
Trad climber
philadelphia, pa
|
|
|
Sep 13, 2010 - 09:39pm PT
|
A quick flip through the 16th edition (1959) and 25th edition (1996) of Machinery's Handbook didn't turn up an "A" or "B" taper standard. According to this place that makes drill bits to that standard the "A" taper is 1" in 20" and the "B" taper is 1" in 10".
Morse tapers are all roughly 1" in 20", but it's not consistent across the line and none are exactly 1" in 20". If you have a big enough lathe it wouldn't be hard to take a skim cut on either the drill or the socket to run a Morse to an "A" (or vice versa), but they might end up being close enough to not bother.
-a.
EDIT- Oh, and +1 on carbide needing either green (silicon carbide) wheels or diamond for sharpening.
|
|
Steve Grossman
Trad climber
Seattle, WA
|
|
|
Sep 13, 2010 - 10:01pm PT
|
The lightest backcountry drilling setup is an SDS to A-Taper adapter with the shank cut off. You have a clearable spud and bit. A little handlebar padding and away you go!
|
|
Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
|
|
|
Topic Author's Reply - Sep 13, 2010 - 10:39pm PT
|
Steve-
The lightest and the cheapest. I've found adapters on eBay for $14 and bits for $5.
Seems like $50 and up is too much.
|
|
Steve Grossman
Trad climber
Seattle, WA
|
|
|
Sep 13, 2010 - 11:17pm PT
|
Spud and a bit for $20 sounds about right. A-taper bits are almost as aesy to source as SDS. I drill mostly 1/2" holes these days and use carbide tipped bits only. I usually drill with Spline to SDS slide adapter with the splines portion cut off.
|
|
mucci
Trad climber
The pitch of Bagalaar above you
|
|
|
Sep 14, 2010 - 12:29am PT
|
I just got an old 5.10 holder, complete with manual and 5/16ths bits brand new. Gotta say the option of 1/4 or 5/16 is nice.
How many bit sizes are able to be used in a standard rawl holder?
Steve how about a picture?
I am not so tech savvy on the A/B taper jargon.
Thanks for the thread!
Mucci
|
|
Wack
climber
Dazevue
|
|
|
Sep 14, 2010 - 09:16am PT
|
"I just use High speed steel bits."
For hand drilling keep it simple. The SDS adds too much length/cost to the system. Tucker Tech was grinding spade tips on HSS bits BITD. The Kid used them on "Keeper of the Flame". I would try to score the 5.10 rig or original Rawl set up. The Leeper holder and bit never worked that well for me.
|
|
Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
|
|
|
Topic Author's Reply - Sep 14, 2010 - 09:52am PT
|
Taper drills simply have a tapered shank that inerts into a tapered hole. A guy named Morse came up with it about the time of the Civil War after he invented the twist drill. It has been in use ever since because it holds tools very solidly and it is very easy and fast to change tools. If you ever worked in a machine shop with drill presses and lathes, you've used morse taper tools. Usually, you remove the tool from the taper by tapping a key or wedge into a hole or slot which knocks the tool out. Morse tapers come in sizes 1 through 7 with 7 being huge.
Masonry hammer drills used to pretty much all use A or B tapers. A was little drills (< 1") and B was big drills. We don't know but an A Taper seems to be pretty close to a 0 Morse.
A Taper Adapters are available so you can use A Taper drills with various chuck systems like SDS. They retail for $20 to $80 but can be found on eBay for $10
http://www.buydrillbits.com/products/masonry/adapters.php?s=ADAPTER-ATaper
A 5/16, 3/8 and 1/2 Taper drills are easy to find for $4-$5
http://www.buydrillbits.com/products/masonry/step2.php?s=ATaper
|
|
Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
|
|
|
Topic Author's Reply - Sep 14, 2010 - 09:58am PT
|
Somebody in India is still making Rawl type holders. Might be a deal here if you want to buy 100 of them. The sizing doesn't make sense. Anybody with a machine shop could easily make these if they bought a taper reamer. Have to make the keys too.
http://www.hiratools.com/RawlPlugeHolder-269-handtool.html
|
|
| Messages 1 - 12 of total 12 in this topic |
|
SuperTopo on the Web
|
Let us know!