Guys this pertains to my power feed post over in BP mill. The brass gear has an odd size key way that I am going to size it to 1/8" I do have a small broaching set with bushings but no 1/8. This brass gear is 2.5" long which going to make key way that length. I going to make a bushing for the key way cutter which is 5/8 OD to fit in bore, but I see that there are different sizes? My little set says it is No 0, w/A cutter so when I go looking for an 1/8 Broach do I need to look for a #0? Looking at auction site I see there are size A,B in the 1/8 broach size. But I can't tell difference. Dumont is a 75.00 cutter so I don't want to make a mistake buy the wrong one. Thanks guys for advice
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1/8 Broach???
- Thread starter Kroll
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A broach that small will not cut a keyway 2 1/2" through the bore, the broach plug would need to be the whole length of the bore, and the broach would likely gag on chips and be broken. Perhaps best to single point a keyway in the lathe.
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- Apr 14, 2014
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The different letter nomenclature refers to the thickness of the spine at the back of the broach. An "A" broach has a 1/8" wide spine, a "B" broach has a 3/16" wide spine, a "C" broach has 3/8" wide spine, a "D" broach has a 9/16" wide spine, …...
Here's a link to a chart giving the dimensions of various keyway broach sizes:
I would suggest first measuring the existing keyway in the brass gear that came with the power feed. The one in mine was not 1/8". It was slightly smaller. I didn't measure it, but I did try to fit a 1/8" key into it and the slot was too narrow. I would also measure the existing keyway in your leadscrew. It's possible the previous owner used an undersized key in a full size keyway.
In my case I was able to broach a full length 1/8" keyway in both my new 2" 6061 ALUMINUM coupling, and enlarge the keyway in the brass gear. I used a standard 1/8" "B" broach and collared bushing. While the bushing was shorter than the coupling I was able to complete the job. The first pass was without any shims. The second pass was with a single shim. Even though the bushing wasn't full length the broach did remove a slight amount of material the entire length.
I then turned the coupling upside down and reinserted the bushing from that end. I aligned the bushing and broach with the slot created by the previous passes, and ran the broach through the coupling with no shim installed. I repeated the process using a single shim.
I once again turned the coupling with the original side up and ran the broach through using 2 shims. I turned the bushing one more time and repeated the process.
The process worked flawlessly on a soft 6061 ALUMINUM coupling, but I'm not sure I'd try it on a steel coupling. It's quite likely the broach would break or load up. Keep in mind the recommended maximum length keyway an 1/8" broach is designed for is 1 1/8".
As for the brass gear I used the same process to enlarge the keyway to 1/8"
Your broach set is a size "00". That's not the size of the broaches themselves, but rather the selection of the broaches included in that particular set. Dumont makes many different sets ranging from "00" (the smallest) to the most complete one number "100"
dumont.com
ON EDIT: I used a "B" broach rather than an "A" broach. I changed the text to reflect the broach size I actually used.
Here's a link to a chart giving the dimensions of various keyway broach sizes:
Keyway Broach 1/16 3/32 1/8 5/32 3/16 1/4 5/16 3/8 7/16 1/2 9/16 5/8 3/4 7/8 1 1-1/4 1-3/8 1-1/2 1-3/4 2 Inch ID 1158-
www.carbideanddiamondtooling.com
I would suggest first measuring the existing keyway in the brass gear that came with the power feed. The one in mine was not 1/8". It was slightly smaller. I didn't measure it, but I did try to fit a 1/8" key into it and the slot was too narrow. I would also measure the existing keyway in your leadscrew. It's possible the previous owner used an undersized key in a full size keyway.
In my case I was able to broach a full length 1/8" keyway in both my new 2" 6061 ALUMINUM coupling, and enlarge the keyway in the brass gear. I used a standard 1/8" "B" broach and collared bushing. While the bushing was shorter than the coupling I was able to complete the job. The first pass was without any shims. The second pass was with a single shim. Even though the bushing wasn't full length the broach did remove a slight amount of material the entire length.
I then turned the coupling upside down and reinserted the bushing from that end. I aligned the bushing and broach with the slot created by the previous passes, and ran the broach through the coupling with no shim installed. I repeated the process using a single shim.
I once again turned the coupling with the original side up and ran the broach through using 2 shims. I turned the bushing one more time and repeated the process.
The process worked flawlessly on a soft 6061 ALUMINUM coupling, but I'm not sure I'd try it on a steel coupling. It's quite likely the broach would break or load up. Keep in mind the recommended maximum length keyway an 1/8" broach is designed for is 1 1/8".
As for the brass gear I used the same process to enlarge the keyway to 1/8"
Your broach set is a size "00". That's not the size of the broaches themselves, but rather the selection of the broaches included in that particular set. Dumont makes many different sets ranging from "00" (the smallest) to the most complete one number "100"
duMont CNC Broaching System - Pilot Precision
duMont CNC is a brand of Pilot Precision that makes CNC Broaches, Indexable Broaches, Industrial Broaches, Rotary Broaches and Keyway Broaches.
dumont.com
ON EDIT: I used a "B" broach rather than an "A" broach. I changed the text to reflect the broach size I actually used.
Last edited:
Thanks guys,Project I have the same issue with mine, where the brass gear goes I cut an 1/8 key way so that I be able to slide the gear little with those shims provided. I planning on making a bushing the length of the gear for the broaching so that cutter be supported full length. Now that I have this information I will know what I am looking for and the differences.And place to shop for broaches. Going shopping for Broach Set
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I've used Dumont broached my entire life at the shop where I worked. Last year I finally invested in a set of my own. For the sizes I needed Dumont was a bit too pricey for my limited use. I finally settled on a Shars #20 set. At the time they were on sale at their eBay store (Discount Machine) for 208.00. I've used them about a dozen times for 1/8", 1/4", and 3/8" keyways. I've had no problems and so far have been happy with the set. A comparable Dumont set generally sells for around $620.00
I just come out of a coma,after looking at prices I think that Shars may be my answer. My beer budget won't allow me a Dumont set. I just afraid buying used cause one would have to figure that cutters are close to being dull. And going to look at their insert tool holders that take the triangle shape inserts which I believe you get 3 cutting tips or 6 cutting tips.
Projectnut,just check and its still 208.00 plus shipping.Going to pull trigger on this be done with it. I tried cut corners last time and it didn't work. Like yourself it be use ever so often. Thanks for post and letting me know what you use.
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- Dec 12, 2016
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Shars also has a 3 broach set with the smaller sizes for around $150.
SHARS 18PCS NO.10 HSS KEYWAY CUTTING BROACH BUSHING SHIM SET NEW R} | eBay
4 broaches & 9 bushings = 18 keyway combinations. Keyway Width. Lenth of Cut. Ratchet device put lever arm in most comfortable position for final application of force. Cap Over Table. Product Code. Four position anvil.
www.ebay.com
That is a good ideal derf and I actually though about it. I try to figure out way to hold one in vise, or make a holder for the key then the vise. But ever so often I figure I will need to cut a key way then spend time making a way to do that which I know is part of the fun. But I just want to go straight to a broaching set and get that part done in short time. I am making a bushing that is longer for the gear,but don't know how wide or how deep to make for the cutter so going to wait till set comes in. I believe that this set will provide me with just about anything come across(fingers cross) MackPete I was looking at that set, in Dumont brand but still out of my league. I settle for the one that Projectnut has which the one that you provided to would have taken care of my needs.But Projectnut offers just little more options for about 50.00 more. Thanks guys for the links and suggestions