I'm getting ready to broach my first keyway with an actual broach .
My question is about the shims , and how thick they need to be .
Measuring the difference between the first and last tooth on the broach
I get .062" and I'm wondering if that is the correct thickness for the
shims .
--
Snag
"They may take our lives but
they'll never take our freedom."
William Wallace

"Snag" wrote in message news:ututu3$1u2oj$1@dont-email.me...

I'm getting ready to broach my first keyway with an actual broach .
My question is about the shims , and how thick they need to be .
Measuring the difference between the first and last tooth on the broach
I get .062" and I'm wondering if that is the correct thickness for the
shims .
Snag

-----------------------------

My 3/16" keyway broach came with an 0.050" shim. For the others I shear
strips of scrap sheetmetal and add one between passes until the key fits. My
guide bushings are all shop-made to eyeballed depth.

Thinner shims leave less unsupported broach, but if the shim is too thin to
hold the bend the broach may pull it through.

On 26/03/2024 16:42, Snag wrote:
> I'm getting ready to broach my first keyway with an actual broach . My
> question is about the shims , and how thick they need to be .
> Measuring the difference between the first and last tooth on the
> broach I get .062" and I'm wondering if that is the correct thickness
> for the shims .

Is it a shop made broach or bought. All my Dumont broaches come with
appropriate shims to cut the keyway to the correct depth.

On 3/26/2024 12:58 PM, David Billington wrote:
> On 26/03/2024 16:42, Snag wrote:
>> I'm getting ready to broach my first keyway with an actual broach . My
>> question is about the shims , and how thick they need to be .
>> Measuring the difference between the first and last tooth on the
>> broach I get .062" and I'm wondering if that is the correct thickness
>> for the shims .
>
> Is it a shop made broach or bought. All my Dumont broaches come with
> appropriate shims to cut the keyway to the correct depth.
>

It's a couple of broaches only from eBay . I machined a guide slug
for it from some 416 SS I bought to "have some on hand in case I need
it" and pushed it with my 12/20* ton HF press . I made shims from some
..050" galvanized sheet I have on hand (being a Pack Rat is often a Good
Thing) and it worked out quite well . I'll never broach another keyway
on the lathe ...

*12 ton frame with a 20 ton air operated jack on it . I have beefed
up the frame where it was necessary .
--
Snag
"They may take our lives but
they'll never take our freedom."
William Wallace

On 3/26/2024 1:40 PM, Snag wrote:
> On 3/26/2024 12:58 PM, David Billington wrote:
>> On 26/03/2024 16:42, Snag wrote:
>>> I'm getting ready to broach my first keyway with an actual broach .
>>> My question is about the shims , and how thick they need to be .
>>> Measuring the difference between the first and last tooth on the
>>> broach I get .062" and I'm wondering if that is the correct thickness
>>> for the shims .
>>
>> Is it a shop made broach or bought. All my Dumont broaches come with
>> appropriate shims to cut the keyway to the correct depth.
>>
>
>   It's a couple of broaches only from eBay . I machined a guide slug
> for it from some 416 SS I bought to "have some on hand in case I need
> it" and pushed it with my 12/20* ton HF press .

416 is nice stuff. Fairly machinable, more rust resistant than chrome
molly (4140/4130), and pretty strong.

I made shims from some
> .050"  galvanized sheet I have on hand (being a Pack Rat is often a Good
> Thing) and it worked out quite well . I'll never broach another keyway
> on the lathe ...

Sometimes you gotta do what you gotta do. Never say never. That
oddball will certainly curse your work shop now.

>   *12 ton frame with a 20 ton air operated jack on it . I have beefed
> up the frame where it was necessary .

I ran a 12 ton air jack on a 12 ton press, and I still tore it apart. I
also bent a 20 ton with a 20 ton jack. That being said, the 6 ton arbor
press has done all the straight broaching I've needed to do so far.

--
Bob La Londe
CNC Molds N Stuff

--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

On 3/26/2024 12:23 PM, Jim Wilkins wrote:
> "Snag"  wrote in message news:ututu3$1u2oj$1@dont-email.me...
>
>   I'm getting ready to broach my first keyway with an actual broach .
> My question is about the shims , and how thick they need to be .
> Measuring the difference between the first and last tooth on the broach
> I get .062" and I'm wondering if that is the correct thickness for the
> shims .
> Snag
>
> -----------------------------
>
> My 3/16" keyway broach came with an 0.050" shim. For the others I shear
> strips of scrap sheetmetal and add one between passes until the key
> fits. My guide bushings are all shop-made to eyeballed depth.
>
> Thinner shims leave less unsupported broach, but if the shim is too thin
> to hold the bend the broach may pull it through.
>

I made a couple of shims from some .050" galvanized sheet . Probably
going to make some more of varying thickness so I can fine tune the
depth . I made the slot in the guide bushing the same depth - measured
from the round - as the width of the broach at the bottom end .
The project got delayed a bit because I stripped the old DRO off the
mill . The new ones are a lot better but there was a good bit of
fabrication to adapt to my mill .
--
Snag
"They may take our lives but
they'll never take our freedom."
William Wallace

"Snag" wrote in message news:utvdti$2bued$1@dont-email.me...
On 3/26/2024 12:23 PM, Jim Wilkins wrote:
......

I made a couple of shims from some .050" galvanized sheet . Probably
going to make some more of varying thickness so I can fine tune the
depth . I made the slot in the guide bushing the same depth - measured
from the round - as the width of the broach at the bottom end .
The project got delayed a bit because I stripped the old DRO off the
mill . The new ones are a lot better but there was a good bit of
fabrication to adapt to my mill .
Snag

-----------------------------

IIRC the proper depth of a key slot is half the width, measured from the cut
edges, so a square key will fit half way into each part. I tend to need
oddballs such as different width slots, the motor/pump shaft (metric?)
existing and the pulley matching one of my broaches, and a custom T shaped
key. There are even offset keys to advance timing on small engines modded
for racing.

On 26/03/2024 20:40, Snag wrote:
> On 3/26/2024 12:58 PM, David Billington wrote:
>> On 26/03/2024 16:42, Snag wrote:
>>> I'm getting ready to broach my first keyway with an actual broach .
>>> My question is about the shims , and how thick they need to be .
>>> Measuring the difference between the first and last tooth on the
>>> broach I get .062" and I'm wondering if that is the correct
>>> thickness for the shims .
>>
>> Is it a shop made broach or bought. All my Dumont broaches come with
>> appropriate shims to cut the keyway to the correct depth.
>>
>
>   It's a couple of broaches only from eBay . I machined a guide slug
> for it from some 416 SS I bought to "have some on hand in case I need
> it" and pushed it with my 12/20* ton HF press . I made shims from some
> .050"  galvanized sheet I have on hand (being a Pack Rat is often a
> Good Thing) and it worked out quite well . I'll never broach another
> keyway on the lathe ...
>
>   *12 ton frame with a 20 ton air operated jack on it . I have beefed
> up the frame where it was necessary .

Maybe some of the information in the Dumont catalogue would be of use.
It gives the broach lengths and the thickness and number of shims
required. https://kar.ca/pdf/catalog/en/Dumont_Catalog.pdf

On 3/27/2024 9:53 AM, David Billington wrote:
> On 26/03/2024 20:40, Snag wrote:
>> On 3/26/2024 12:58 PM, David Billington wrote:
>>> On 26/03/2024 16:42, Snag wrote:
>>>> I'm getting ready to broach my first keyway with an actual broach .
>>>> My question is about the shims , and how thick they need to be .
>>>> Measuring the difference between the first and last tooth on the
>>>> broach I get .062" and I'm wondering if that is the correct
>>>> thickness for the shims .
>>>
>>> Is it a shop made broach or bought. All my Dumont broaches come with
>>> appropriate shims to cut the keyway to the correct depth.
>>>
>>
>>   It's a couple of broaches only from eBay . I machined a guide slug
>> for it from some 416 SS I bought to "have some on hand in case I need
>> it" and pushed it with my 12/20* ton HF press . I made shims from some
>> .050"  galvanized sheet I have on hand (being a Pack Rat is often a
>> Good Thing) and it worked out quite well . I'll never broach another
>> keyway on the lathe ...
>>
>>   *12 ton frame with a 20 ton air operated jack on it . I have beefed
>> up the frame where it was necessary .
>
> Maybe some of the information in the Dumont catalogue would be of use.
> It gives the broach lengths and the thickness and number of shims
> required. https://kar.ca/pdf/catalog/en/Dumont_Catalog.pdf
>

I figure the shim should be the same thickness as the difference
between the first and last tooth - mine measure .062 . This will keep
the "pilot" on the end in contact with the bottom of the groove being
cut . I noticed a variation in the depth on that keyway I cut yesterday
.... I think because the broach was not bottomed out in the groove in the
pilot bushing .
--
Snag
"They may take our lives but
they'll never take our freedom."
William Wallace

On 27/03/2024 17:25, Snag wrote:
> On 3/27/2024 9:53 AM, David Billington wrote:
>> On 26/03/2024 20:40, Snag wrote:
>>> On 3/26/2024 12:58 PM, David Billington wrote:
>>>> On 26/03/2024 16:42, Snag wrote:
>>>>> I'm getting ready to broach my first keyway with an actual broach
>>>>> . My question is about the shims , and how thick they need to be .
>>>>> Measuring the difference between the first and last tooth on the
>>>>> broach I get .062" and I'm wondering if that is the correct
>>>>> thickness for the shims .
>>>>
>>>> Is it a shop made broach or bought. All my Dumont broaches come
>>>> with appropriate shims to cut the keyway to the correct depth.
>>>>
>>>
>>>   It's a couple of broaches only from eBay . I machined a guide slug
>>> for it from some 416 SS I bought to "have some on hand in case I
>>> need it" and pushed it with my 12/20* ton HF press . I made shims
>>> from some .050"  galvanized sheet I have on hand (being a Pack Rat
>>> is often a Good Thing) and it worked out quite well . I'll never
>>> broach another keyway on the lathe ...
>>>
>>>   *12 ton frame with a 20 ton air operated jack on it . I have
>>> beefed up the frame where it was necessary .
>>
>> Maybe some of the information in the Dumont catalogue would be of
>> use. It gives the broach lengths and the thickness and number of
>> shims required. https://kar.ca/pdf/catalog/en/Dumont_Catalog.pdf
>>
>
>   I figure the shim should be the same thickness as the difference
> between the first and last tooth - mine measure .062 . This will keep
> the "pilot" on the end in contact with the bottom of the groove being
> cut . I noticed a variation in the depth on that keyway I cut
> yesterday ... I think because the broach was not bottomed out in the
> groove in the pilot bushing .

I've seen that with mine before like yesterday where the top of the
broach was leaning towards me a bit, cutting edges forward, so I
corrected it for the second pass for a 4mm key. I'll check my broaches
tomorrow and see how the shim thickness correlates to the height
increase along the broach and report back.

On 3/27/2024 12:42 PM, David Billington wrote:
> On 27/03/2024 17:25, Snag wrote:
>> On 3/27/2024 9:53 AM, David Billington wrote:
>>> On 26/03/2024 20:40, Snag wrote:
>>>> On 3/26/2024 12:58 PM, David Billington wrote:
>>>>> On 26/03/2024 16:42, Snag wrote:
>>>>>> I'm getting ready to broach my first keyway with an actual broach
>>>>>> . My question is about the shims , and how thick they need to be .
>>>>>> Measuring the difference between the first and last tooth on the
>>>>>> broach I get .062" and I'm wondering if that is the correct
>>>>>> thickness for the shims .
>>>>>
>>>>> Is it a shop made broach or bought. All my Dumont broaches come
>>>>> with appropriate shims to cut the keyway to the correct depth.
>>>>>
>>>>
>>>>   It's a couple of broaches only from eBay . I machined a guide slug
>>>> for it from some 416 SS I bought to "have some on hand in case I
>>>> need it" and pushed it with my 12/20* ton HF press . I made shims
>>>> from some .050"  galvanized sheet I have on hand (being a Pack Rat
>>>> is often a Good Thing) and it worked out quite well . I'll never
>>>> broach another keyway on the lathe ...
>>>>
>>>>   *12 ton frame with a 20 ton air operated jack on it . I have
>>>> beefed up the frame where it was necessary .
>>>
>>> Maybe some of the information in the Dumont catalogue would be of
>>> use. It gives the broach lengths and the thickness and number of
>>> shims required. https://kar.ca/pdf/catalog/en/Dumont_Catalog.pdf
>>>
>>
>>   I figure the shim should be the same thickness as the difference
>> between the first and last tooth - mine measure .062 . This will keep
>> the "pilot" on the end in contact with the bottom of the groove being
>> cut . I noticed a variation in the depth on that keyway I cut
>> yesterday ... I think because the broach was not bottomed out in the
>> groove in the pilot bushing .
>
> I've seen that with mine before like yesterday where the top of the
> broach was leaning towards me a bit, cutting edges forward, so I
> corrected it for the second pass for a 4mm key. I'll check my broaches
> tomorrow and see how the shim thickness correlates to the height
> increase along the broach and report back.
>

This was a case of I started the cut on the lathe , cranking the
carriage forward and back . I think the taper would have self-corrected
if I'd used a .062" shim instead of the .050" .
--
Snag
"They may take our lives but
they'll never take our freedom."
William Wallace

On 27/03/2024 18:55, Snag wrote:
> On 3/27/2024 12:42 PM, David Billington wrote:
>> On 27/03/2024 17:25, Snag wrote:
>>> On 3/27/2024 9:53 AM, David Billington wrote:
>>>> On 26/03/2024 20:40, Snag wrote:
>>>>> On 3/26/2024 12:58 PM, David Billington wrote:
>>>>>> On 26/03/2024 16:42, Snag wrote:
>>>>>>> I'm getting ready to broach my first keyway with an actual
>>>>>>> broach . My question is about the shims , and how thick they
>>>>>>> need to be . Measuring the difference between the first and last
>>>>>>> tooth on the broach I get .062" and I'm wondering if that is the
>>>>>>> correct thickness for the shims .
>>>>>>
>>>>>> Is it a shop made broach or bought. All my Dumont broaches come
>>>>>> with appropriate shims to cut the keyway to the correct depth.
>>>>>>
>>>>>
>>>>>   It's a couple of broaches only from eBay . I machined a guide
>>>>> slug for it from some 416 SS I bought to "have some on hand in
>>>>> case I need it" and pushed it with my 12/20* ton HF press . I made
>>>>> shims from some .050"  galvanized sheet I have on hand (being a
>>>>> Pack Rat is often a Good Thing) and it worked out quite well .
>>>>> I'll never broach another keyway on the lathe ...
>>>>>
>>>>>   *12 ton frame with a 20 ton air operated jack on it . I have
>>>>> beefed up the frame where it was necessary .
>>>>
>>>> Maybe some of the information in the Dumont catalogue would be of
>>>> use. It gives the broach lengths and the thickness and number of
>>>> shims required. https://kar.ca/pdf/catalog/en/Dumont_Catalog.pdf
>>>>
>>>
>>>   I figure the shim should be the same thickness as the difference
>>> between the first and last tooth - mine measure .062 . This will
>>> keep the "pilot" on the end in contact with the bottom of the groove
>>> being cut . I noticed a variation in the depth on that keyway I cut
>>> yesterday ... I think because the broach was not bottomed out in the
>>> groove in the pilot bushing .
>>
>> I've seen that with mine before like yesterday where the top of the
>> broach was leaning towards me a bit, cutting edges forward, so I
>> corrected it for the second pass for a 4mm key. I'll check my
>> broaches tomorrow and see how the shim thickness correlates to the
>> height increase along the broach and report back.
>>
>
>   This was a case of I started the cut on the lathe , cranking the
> carriage forward and back . I think the taper would have
> self-corrected if I'd used a .062" shim instead of the .050" .

This is what I measured.

Broach list Dumont No 10 set
Size    Start     End     Diff    Teeth     /Tooth    Shim
1/8"    0.390    0.421     0.031    16    0.0021    0.031 x 1
3/16"    0.377    0.429    0.052    16    0.0035    0.050 x 1
1/4"    0.587    0.651    0.064    22    0.0030    0.062 x 1
3/8"    0.569    0.633    0.064    22    0.0030    0.062 x 2

The /Tooth is Diff /(Teeth - 1) . Looks like your original assumption
about the shim thickness is correct.

On 3/28/2024 5:19 PM, David Billington wrote:
> On 27/03/2024 18:55, Snag wrote:
>> On 3/27/2024 12:42 PM, David Billington wrote:
>>> On 27/03/2024 17:25, Snag wrote:
>>>> On 3/27/2024 9:53 AM, David Billington wrote:
>>>>> On 26/03/2024 20:40, Snag wrote:
>>>>>> On 3/26/2024 12:58 PM, David Billington wrote:
>>>>>>> On 26/03/2024 16:42, Snag wrote:
>>>>>>>> I'm getting ready to broach my first keyway with an actual
>>>>>>>> broach . My question is about the shims , and how thick they
>>>>>>>> need to be . Measuring the difference between the first and last
>>>>>>>> tooth on the broach I get .062" and I'm wondering if that is the
>>>>>>>> correct thickness for the shims .
>>>>>>>
>>>>>>> Is it a shop made broach or bought. All my Dumont broaches come
>>>>>>> with appropriate shims to cut the keyway to the correct depth.
>>>>>>>
>>>>>>
>>>>>>   It's a couple of broaches only from eBay . I machined a guide
>>>>>> slug for it from some 416 SS I bought to "have some on hand in
>>>>>> case I need it" and pushed it with my 12/20* ton HF press . I made
>>>>>> shims from some .050"  galvanized sheet I have on hand (being a
>>>>>> Pack Rat is often a Good Thing) and it worked out quite well .
>>>>>> I'll never broach another keyway on the lathe ...
>>>>>>
>>>>>>   *12 ton frame with a 20 ton air operated jack on it . I have
>>>>>> beefed up the frame where it was necessary .
>>>>>
>>>>> Maybe some of the information in the Dumont catalogue would be of
>>>>> use. It gives the broach lengths and the thickness and number of
>>>>> shims required. https://kar.ca/pdf/catalog/en/Dumont_Catalog.pdf
>>>>>
>>>>
>>>>   I figure the shim should be the same thickness as the difference
>>>> between the first and last tooth - mine measure .062 . This will
>>>> keep the "pilot" on the end in contact with the bottom of the groove
>>>> being cut . I noticed a variation in the depth on that keyway I cut
>>>> yesterday ... I think because the broach was not bottomed out in the
>>>> groove in the pilot bushing .
>>>
>>> I've seen that with mine before like yesterday where the top of the
>>> broach was leaning towards me a bit, cutting edges forward, so I
>>> corrected it for the second pass for a 4mm key. I'll check my
>>> broaches tomorrow and see how the shim thickness correlates to the
>>> height increase along the broach and report back.
>>>
>>
>>   This was a case of I started the cut on the lathe , cranking the
>> carriage forward and back . I think the taper would have
>> self-corrected if I'd used a .062" shim instead of the .050" .
>
> This is what I measured.
>
> Broach list Dumont No 10 set
> Size    Start     End     Diff    Teeth     /Tooth    Shim
> 1/8"    0.390    0.421     0.031    16    0.0021    0.031 x 1
> 3/16"    0.377    0.429    0.052    16    0.0035    0.050 x 1
> 1/4"    0.587    0.651    0.064    22    0.0030    0.062 x 1
> 3/8"    0.569    0.633    0.064    22    0.0030    0.062 x 2
>
> The /Tooth is Diff /(Teeth - 1) . Looks like your original assumption
> about the shim thickness is correct.
>
>

Thanks for getting back with that info . It seemed intuitive , but ya
never know . Now we know .
--
Snag
"They may take our lives but
they'll never take our freedom."
William Wallace