HobbyKing.com New Products Flash Sale
 
Thread Tools
Old Apr 18, 2012, 03:55 PM
Andrew Mawson
Guest
n/a Posts
Dog Clutch tooth shape

Are dog clutch teeth supposed usually to have 90 degree flanks, or are they
sometimes inclined like an acme thread?

I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with a
1.1kw motor, and pressing the treadle allows a dog clutch to engage via
spring pressure rotating eccentrics which pull the upper blade through the
material. Recently under full width cuts the clutch has taken to not fully
engaging, and jumping out of engagement. The flanks are obviously fairly
worn and need re-machining, but what shape to make them - they could have
been inclined or this could be the wear with them starting off
perpendicular - any suggestions?

AWEM
Old Apr 18, 2012, 04:25 PM
Pete
Guest
n/a Posts
Re: Dog Clutch tooth shape

"Andrew Mawson" <andrew@please_remove_me.mawson.org.uk> wrote in message
news:wa2dnZ3Wp-eqgRLSnZ2dnUVZ8t2dnZ2d@bt.com...

> Are dog clutch teeth supposed usually to have 90 degree flanks, or are
> they sometimes inclined like an acme thread?
>
> I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with
> a 1.1kw motor, and pressing the treadle allows a dog clutch to engage via
> spring pressure rotating eccentrics which pull the upper blade through the
> material. Recently under full width cuts the clutch has taken to not fully
> engaging, and jumping out of engagement. The flanks are obviously fairly
> worn and need re-machining, but what shape to make them - they could have
> been inclined or this could be the wear with them starting off
> perpendicular - any suggestions?
>
> AWEM
>


Gearbox dogs are usually cut slightly the other way (undercut), and they
have no problem engaging/disngaging even under a bit of a load.
Old Apr 18, 2012, 05:31 PM
Mark Rand
Guest
n/a Posts
Re: Dog Clutch tooth shape

On Wed, 18 Apr 2012 20:55:39 +0100, "Andrew Mawson"
<andrew@please_remove_me.mawson.org.uk> wrote:


>Are dog clutch teeth supposed usually to have 90 degree flanks, or are they
>sometimes inclined like an acme thread?
>
>I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with a
>1.1kw motor, and pressing the treadle allows a dog clutch to engage via
>spring pressure rotating eccentrics which pull the upper blade through the
>material. Recently under full width cuts the clutch has taken to not fully
>engaging, and jumping out of engagement. The flanks are obviously fairly
>worn and need re-machining, but what shape to make them - they could have
>been inclined or this could be the wear with them starting off
>perpendicular - any suggestions?
>
>AWEM



If there is any possibility that they need to engage while moving relative to
each other, they either need a bit of an inclined flank or a lot of clearance
to lessen the likelihood of fractional engagement and damage to the corners of
the teeth. Springs will help the clutch to stay engaged against the pressure
from the inclined teeth.

How's about the form used by Bridgeport clutches as a first approximation?

Regards
Mark Rand
RTFM
Old Apr 18, 2012, 05:44 PM
Andrew Mawson
Guest
n/a Posts
Re: Dog Clutch tooth shape

"Mark Rand" wrote in message
news:nacuo71kk6tcphfn4khq3g9t20ribloi8n@4ax.com...

>
>On Wed, 18 Apr 2012 20:55:39 +0100, "Andrew Mawson"
><andrew@please_remove_me.mawson.org.uk> wrote:
>

>>Are dog clutch teeth supposed usually to have 90 degree flanks, or are
>>they
>>sometimes inclined like an acme thread?
>>
>>I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with
>>a
>>1.1kw motor, and pressing the treadle allows a dog clutch to engage via
>>spring pressure rotating eccentrics which pull the upper blade through the
>>material. Recently under full width cuts the clutch has taken to not fully
>>engaging, and jumping out of engagement. The flanks are obviously fairly
>>worn and need re-machining, but what shape to make them - they could have
>>been inclined or this could be the wear with them starting off
>>perpendicular - any suggestions?
>>
>>AWEM

>
>
>If there is any possibility that they need to engage while moving relative
>to
>each other, they either need a bit of an inclined flank or a lot of
>clearance
>to lessen the likelihood of fractional engagement and damage to the corners
>of
>the teeth. Springs will help the clutch to stay engaged against the
>pressure
>from the inclined teeth.
>
>How's about the form used by Bridgeport clutches as a first approximation?
>
>Regards
>Mark Rand
>RTFM



A big spring pushes them into engagement, a foot operated peg bears on an
axial cam profile to pull them apart - this same peg eventually falls into a
hole that stops the rotation after one revolution. They will always have
relative rotation until engaged as the flywheel is spinning and the shaft
holding the eccentrics is stationary until the clutch engages with a
frightening whack! Are you meaning the Bridgeport back gear dog clutch?
Trouble is the bits are pretty massive, and removal is no five minute task!
I'm tempted to go at them with an angle grinder in situ!

AWEM
Old Apr 18, 2012, 06:48 PM
Mark Rand
Guest
n/a Posts
Re: Dog Clutch tooth shape

On Wed, 18 Apr 2012 22:44:05 +0100, "Andrew Mawson"
<andrew@please_remove_me.mawson.org.uk> wrote:


>"Mark Rand" wrote in message
>news:nacuo71kk6tcphfn4khq3g9t20ribloi8n@4ax.com.. .

>>
>>On Wed, 18 Apr 2012 20:55:39 +0100, "Andrew Mawson"
>><andrew@please_remove_me.mawson.org.uk> wrote:
>>

>>>Are dog clutch teeth supposed usually to have 90 degree flanks, or are
>>>they
>>>sometimes inclined like an acme thread?
>>>
>>>I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with
>>>a
>>>1.1kw motor, and pressing the treadle allows a dog clutch to engage via
>>>spring pressure rotating eccentrics which pull the upper blade through the
>>>material. Recently under full width cuts the clutch has taken to not fully
>>>engaging, and jumping out of engagement. The flanks are obviously fairly
>>>worn and need re-machining, but what shape to make them - they could have
>>>been inclined or this could be the wear with them starting off
>>>perpendicular - any suggestions?
>>>
>>>AWEM

>>
>>
>>If there is any possibility that they need to engage while moving relative
>>to
>>each other, they either need a bit of an inclined flank or a lot of
>>clearance
>>to lessen the likelihood of fractional engagement and damage to the corners
>>of
>>the teeth. Springs will help the clutch to stay engaged against the
>>pressure
>>from the inclined teeth.
>>
>>How's about the form used by Bridgeport clutches as a first approximation?
>>
>>Regards
>>Mark Rand
>>RTFM

>
>
>A big spring pushes them into engagement, a foot operated peg bears on an
>axial cam profile to pull them apart - this same peg eventually falls into a
>hole that stops the rotation after one revolution. They will always have
>relative rotation until engaged as the flywheel is spinning and the shaft
>holding the eccentrics is stationary until the clutch engages with a
>frightening whack! Are you meaning the Bridgeport back gear dog clutch?
>Trouble is the bits are pretty massive, and removal is no five minute task!
>I'm tempted to go at them with an angle grinder in situ!
>
>AWEM



Yes, the back gear clutch was what I was thinking of (not that I've got one,
since I've got a Beaver :).

Possibly, start with the angle grinder and finish with the die grinder and
some blue to try to get reasonably equal engagement on the teeth?

When do you get to the point of competing directly with Tata/BSC Port Talbot+
Llanwern? :-)


Regards
Mark Rand
RTFM
Old Apr 19, 2012, 02:23 AM
mark@ems-fife.co.uk
Guest
n/a Posts
Re: Dog Clutch tooth shape

On Apr 18, 11:48 pm, Mark Rand <ra...@internettie.co.uk> wrote:


> since I've got a Beaver :).


Now why doesn`t that surprise me?

>>>>>>>>>>>>>>>


> When do you get to the point of competing directly with Tata/BSC Port Talbot+
> Llanwern? :-)


More like E.M.R.
Old Apr 19, 2012, 03:49 AM
Andrew Mawson
Guest
n/a Posts
Re: Dog Clutch tooth shape

"Mark Rand" wrote in message
news:vnguo7143u6a6lkvrq4gkjg3g9b6786lnu@4ax.com...

>
>When do you get to the point of competing directly with Tata/BSC Port
>Talbot+
>Llanwern? :-)
>
>
>Regards
>Mark Rand
>RTFM



It's only a modest little guillotine !

AWEM
Old Apr 19, 2012, 04:00 PM
John S
Guest
n/a Posts
Re: Dog Clutch tooth shape

On Apr 18, 8:55 pm, "Andrew Mawson"
<andrew@please_remove_me.mawson.org.uk> wrote:

> Are dog clutch teeth supposed usually to have 90 degree flanks, or are they
> sometimes inclined like an acme thread?
>
> I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with a
> 1.1kw motor, and pressing the treadle allows a dog clutch to engage via
> spring pressure rotating eccentrics which pull the upper blade through the
> material. Recently under full width cuts the clutch has taken to not fully
> engaging, and jumping out of engagement. The flanks are obviously fairly
> worn and need re-machining, but what shape to make them - they could have
> been inclined or this could be the wear with them starting off
> perpendicular - any suggestions?
>
> AWEM


Normally 5 to 7 degrees undercut, and nothing wrong with the angle
grinder approach.

John S.
Old Apr 19, 2012, 04:53 PM
ChrisQ
Guest
n/a Posts
Re: Dog Clutch tooth shape

On 04/19/12 20:00, John S wrote:

> On Apr 18, 8:55 pm, "Andrew Mawson"
> <andrew@please_remove_me.mawson.org.uk> wrote:

>> Are dog clutch teeth supposed usually to have 90 degree flanks, or are they
>> sometimes inclined like an acme thread?
>>
>> I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with a
>> 1.1kw motor, and pressing the treadle allows a dog clutch to engage via
>> spring pressure rotating eccentrics which pull the upper blade through the
>> material. Recently under full width cuts the clutch has taken to not fully
>> engaging, and jumping out of engagement. The flanks are obviously fairly
>> worn and need re-machining, but what shape to make them - they could have
>> been inclined or this could be the wear with them starting off
>> perpendicular - any suggestions?
>>
>> AWEM

>
> Normally 5 to 7 degrees undercut, and nothing wrong with the angle
> grinder approach.
>
> John S.


You can also use hard welding rods to build up the worn edges prior to
using the
angle grinder. The advantage being that you then only have a small amount
of metal to remove and it avoids disturbing the overall profile and sizes.

Used that on an old geared head drill's dog clutches (scrapyard) many
years ago
and it still works...

Regards,

Chris
Old Apr 19, 2012, 04:56 PM
ChrisQ
Guest
n/a Posts
Re: Dog Clutch tooth shape

On 04/19/12 20:53, ChrisQ wrote:

> On 04/19/12 20:00, John S wrote:

>> On Apr 18, 8:55 pm, "Andrew Mawson"
>> <andrew@please_remove_me.mawson.org.uk> wrote:

>>> Are dog clutch teeth supposed usually to have 90 degree flanks, or
>>> are they
>>> sometimes inclined like an acme thread?
>>>
>>> I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel
>>> with a
>>> 1.1kw motor, and pressing the treadle allows a dog clutch to engage via
>>> spring pressure rotating eccentrics which pull the upper blade
>>> through the
>>> material. Recently under full width cuts the clutch has taken to not
>>> fully
>>> engaging, and jumping out of engagement. The flanks are obviously fairly
>>> worn and need re-machining, but what shape to make them - they could
>>> have
>>> been inclined or this could be the wear with them starting off
>>> perpendicular - any suggestions?
>>>
>>> AWEM

>>
>> Normally 5 to 7 degrees undercut, and nothing wrong with the angle
>> grinder approach.
>>
>> John S.

>
> You can also use hard welding rods to build up the worn edges prior to
> using the
> angle grinder. The advantage being that you then only have a small amount
> of metal to remove and it avoids disturbing the overall profile and sizes.
>
> Used that on an old geared head drill's dog clutches (scrapyard) many
> years ago
> and it still works...
>
> Regards,
>
> Chris
>
>


Of course, another answer might be that the thing is out of adjustment, in
that with full width cuts, the clutch may still be iengaging when the load
appears ?...

Regards,

Chris
Old Apr 19, 2012, 05:40 PM
Jim Wilkins
Guest
n/a Posts
Re: Dog Clutch tooth shape

"ChrisQ" <meru@devnull.com> wrote

>
> You can also use hard welding rods to build up the worn edges prior
> to using the
> angle grinder. The advantage being that you then only have a small
> amount
> of metal to remove and it avoids disturbing the overall profile and
> sizes.
>
> Used that on an old geared head drill's dog clutches (scrapyard)
> many years ago
> and it still works...
>
> Chris


I rebuilt the edge of a wood splitting maul, which my uncle had used
to trim a granite porch step, with snowplow hard surfacing rod . The
new end was easy enough to grind sharp and has held up well, though it
hits only oak now.

Beating an axe to death against a rock was greatly preferable to
ignoring my grandmother's request.

jsw
 


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Single-Tooth-Single-Direction winding technique modisc Electric Motor Design and Construction 8 Oct 13, 2014 09:15 PM
Alert Trex 600 aluminum clutch fan breaks clutch mount!? Heads_up Fuel Heli Talk 0 Dec 19, 2011 09:08 PM
Help! In need of a plane that is in the shape of cat or dog. rcrich Foamies (Scratchbuilt) 12 Dec 06, 2011 04:40 PM
Discussion 2.4 Ghz / blue tooth modules? nickwad Multirotor Talk 1 Sep 15, 2011 07:12 AM