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Ian B
01-17-2009, 10:32 AM
Found these 2 videos, thought they might be of interest:

http://www.poliangolar.com/l_eng/04a_poliangolar2006.htm
http://www.poliangolar.com/l_eng/04b_polikey2006.htm

The Poliangolar looks like something that an HSM'er might just knock together...

Ian

tony ennis
01-17-2009, 10:45 AM
The pr0n soundtrack is great too!

I liked the power-broach thing. The first tool made my head hurt.

Fasttrack
01-17-2009, 11:50 AM
:) Looks like a rotary broach for use in a mill spindle instead of a lathe tailstock. Thats pretty neat. A rotary broach has been added to my to-do list, but we'll see how long it takes to get there ;)


http://www.slatertools.com/video.htm

http://bbs.homeshopmachinist.net/showthread.php?t=32122&highlight=rotary+broach

hawgwrench
01-17-2009, 12:19 PM
hmmm....the first one reminds me of a few botched mandrel's I've turned out...

Frank Ford
01-17-2009, 12:59 PM
Rotary broaching is really cool. I got a Slater from eBay, and now make my own bits from dead end mills:

http://www.frets.com/HomeShopTech/Tooling/BroachMaking/broachmaking12.jpg

http://www.frets.com/HomeShopTech/Tooling/BroachMaking/broachmaking15.jpg

Here;s the rest:

http://www.frets.com/HomeShopTech/Tooling/BroachMaking/broachmaking.html

Paul Alciatore
01-17-2009, 01:55 PM
I believe making a rotary broach would be possible in the home shop. It is mainly a tool holder set in a bearing that is at an small angle to the main axis. Needs a good thrust bearing as this would be a heavy load. Regular ball bearings would do for the radial bearings. And a simple hole with a set screw would probably do to mount the tool. You would need to do a bit of work on the angle and the geometry of the tool vs the desired hole, but with CAD it should be doable.

I think I saw some plans for one some time back, possibly here or on that "other" board.

Frank Ford
01-17-2009, 02:19 PM
If you haven't been there, check the Slater web site:

http://www.slatertools.com

Both videos are interesting.

If memory serves, the tool wobbles at a one degree angle.

Teenage_Machinist
01-17-2009, 04:26 PM
Somebody made complete plans and started physical making of it.

It is not a terribly complex tool. I believe that the cost of Slater ones are extra profit due to low competition.


A very simple one might be made with only three parts: a spindle, a body, and a tool. Plus one needle and one radial bearing.

Spin Doctor
01-17-2009, 04:30 PM
I have always wondered just how much problem chip removal is

dp
01-17-2009, 04:35 PM
This came up quite recently here: http://bbs.homeshopmachinist.net/showthread.php?t=27232

Fasttrack
01-17-2009, 05:10 PM
Frank - the slater ones are canted very slightly from the longitudinal lathe axis. I think that 1 or 2 degrees is correct, iirc. However, according to the article that you all referred me to in HSM September 2002, they found they had better results by a 5-6* offset. This requires that your broach be ground to 6-7* relief, respectively. Not sure why there is such a difference in the two angles, though.

mochinist
01-17-2009, 05:23 PM
It is not a terribly complex tool. I believe that the cost of Slater ones are extra profit due to low competition.
I see you complain about the price of quality tools quite a bit and I look forward to you going into manufacturing and finally making quality tools for an affordable price(for a limited market) for some of to buy. good luck:)

Mark Hockett
01-18-2009, 02:02 AM
I learned a hard lesson about rotary broaches last week. I had a job that requires 600 3/4" square holes in 1/4" steel plate. I pulled out the Slater rotary broach and started running the job. Made it through about 60 holes and my spindle started getting noisy. $3500 dollars to rebuild the spindle and the spindle rebuilder tells me that those things are very hard on spindles and they see a lot of spindle damage from them. I think that will be the last time my machine sees a rotary broach.

peter08
01-21-2009, 09:47 AM
Chip removal isn't a big deal. Usually you can just drill out the hole to the same depth as the pre-drill and you'll clean out the chips. If absolutely no chips are allowed, they can be removed with a boring tool or a flat bottom drill. A recess at the bottom of the hole will allow the chip to break clean. The recess diameter should be larger than the the major diameter of the form being broached.

Fasttrack
01-21-2009, 12:12 PM
I learned a hard lesson about rotary broaches last week. I had a job that requires 600 3/4" square holes in 1/4" steel plate. I pulled out the Slater rotary broach and started running the job. Made it through about 60 holes and my spindle started getting noisy. $3500 dollars to rebuild the spindle and the spindle rebuilder tells me that those things are very hard on spindles and they see a lot of spindle damage from them. I think that will be the last time my machine sees a rotary broach.


Out of curiosity, what was the machine that gave up the ghost?

Mark Hockett
01-21-2009, 03:24 PM
Out of curiosity, what was the machine that gave up the ghost?
My Fadal 15-XT with a CAT 40 spindle. It is making a slight growling noise and has not had a catastrophic failure yet. I am in the middle of a big job that will run through the end of the month, after that I will swap it out.

pcarpenter
01-21-2009, 05:54 PM
I would think that it almost has to result in a lot of tiny axial "impacts" on the spindle bearings. We talk about spindle bearings and the great radial and even axial loads the bearings can take, but *impacts* on a pair of very hard surfaces like a ball and its associated race could make for the sorts of expensive replacements like Mark is talking about.

I don't even like flycutters (or two-point insert milling cutters) because of the hammering spindle bearings take.

Paul

oldtiffie
01-21-2009, 07:02 PM
I learned a hard lesson about rotary broaches last week. I had a job that requires 600 3/4" square holes in 1/4" steel plate. I pulled out the Slater rotary broach and started running the job. Made it through about 60 holes and my spindle started getting noisy. $3500 dollars to rebuild the spindle and the spindle rebuilder tells me that those things are very hard on spindles and they see a lot of spindle damage from them. I think that will be the last time my machine sees a rotary broach.

Thanks Mark.

Very timely pertinent post.

In physics it more or less says that for every action there is a reaction.

A bit of even a cursory look at the action of the rotary broaches invites but does not always get a consideration of the loads and resultant reactions on the machine be it a lathe or mill etc.

I am not sure that quills and spindles were designed with impact loads that are not far short of those in "hammer drilling" or demolition tools in mind. Not only are the loads axial but also "conical".

In a lathe it may well be worse than a heavy-duty production mill as the reactive load in a lathe is taken on the contact (arc) tail-stock body to quill but also on the tail-stock screw and nut as well as the thrust assembly. The loads on the lathe spindle and its bearings don't need too much imagination either.

This scenario does not bode well for the accuracy required of quills and the part/s in and with which they operate.

Rotary broaches are well off my "nice to have" list as I think that if I bought one I would regret it and (ruefully) put it on my "it seemed like a good idea at the time" and "well that taught me a bl**dy good/expensive lesson" lists.

Mark Hockett
01-21-2009, 07:30 PM
I should also mention that I was using the large size Slater rotary broach with a 3/4" square cutter. The broach and CAT arbor were about 10-15 pounds hanging in the spindle. My machine was running at about 120% on the spindle load meter, so the outcome was not surprising. I was able to get the customer to buy off on an 1/8" radius in the corners so I just used a 1/4" end mill and finished the other 590 holes.
I think a lathe would handle the broach better because of the larger spindle bearings and a mill would probably handle the smaller rotary broach OK, I am just a little gun shy about them now.

peter08
02-05-2009, 11:48 AM
At Slater, we get a lot of orders for broaches with corner radius for that very reason. Sometimes it's the difference between the operation even working or not. Depending on the material, pre-drill size and power of the machine, it may not be possible to broach even a small hex or square sometimes. We most often offer a 'spun ground diameter', using a radius from the center of the broach. I most often reference this feature for broach tool life, but after this thread, I guess I will also mention broach holder life and machine life! I'm wondering if resharpening the broaches more often may or may not have helped out too.

lane
02-05-2009, 06:36 PM
I have always wondered just how much problem chip removal is

Their is no chip removal .They are rolled up in to the bottom of the hole.

aboard_epsilon
02-05-2009, 07:10 PM
Going to try tomorrow, making a hex hole ..

Will be drilling a hole the same diameter as the inside of the hex

and hammering in an Allan key that is tapered .

it will turn out looking more like a torx sort of hole
but as long as it does the job ..im happy
I've made tool post keys by this method before and got great results ...they were square though

not tried hex ...if i have success, will post some pics ..wish me luck!!!

all the best.markj

Teenage_Machinist
02-05-2009, 11:22 PM
One could remove them with a drill, partially.

Mcgyver
02-05-2009, 11:56 PM
Paul, I'd thought of making one as well, but Mark's post spooked me on it a bit....guess i'll carry on without, from a recent post of mine on PM about hexes....I have no slotting head, sinker edm or rotary broach. I know TM would just make one each :D but I went the old fashioned way


Filing. This can be very accurate. I read somewhere it was an apprentice's assignment to file a hex male and female that fit in each position and and have no movement. Thought i test myself. I cheated on the male hex and used the mill, but the female I filed and it worked out well. Laid out the hex with dividers, drilled a pilot and roughly filed the hex. The trick I found for a perfect fit is when you get very close, use some blue on the male hex and fine cut needle files to identify where its still tight. cheaper than buying a broach or rotary broach and faster than waiting for it to arrive

http://i20.photobucket.com/albums/b201/michael0100/upt/closeupoffiledhex.jpg


Forging these were forged

http://i20.photobucket.com/albums/b201/michael0100/sockets/completedsockets.jpg

and the home made broach

http://i20.photobucket.com/albums/b201/michael0100/broaching/homemadebroaches.jpg

I've decided to modernize my approach to internal hex making so bought a 60 year old shaper

tattoomike68
02-06-2009, 02:27 AM
I learned a hard lesson about rotary broaches last week. I had a job that requires 600 3/4" square holes in 1/4" steel plate. I pulled out the Slater rotary broach and started running the job. Made it through about 60 holes and my spindle started getting noisy. $3500 dollars to rebuild the spindle and the spindle rebuilder tells me that those things are very hard on spindles and they see a lot of spindle damage from them. I think that will be the last time my machine sees a rotary broach.

That was a job for an iron worker and just punch the holes.
Rotary broachs run fine on a lathe where you have way more beef in the headstock and spindle.

peter08
02-09-2009, 04:57 PM
Nice pics Mcgyver

lazlo
02-09-2009, 06:23 PM
Forging these were forged

Michael, did you actually forge those yourself? :) I'm assuming those are forged sockets that you silver-soldered onto drill rod? :)

Mcgyver
02-09-2009, 06:53 PM
Michael, did you actually forge those yourself? :)

yes sir :)

one set in BA and one in Model Engineer sizes, i think its ME in the pic

Fasttrack
02-09-2009, 08:29 PM
For the broaches, did you turn the steps on the lathe and then mill the hexagon or ... ?