MWF FEED
17th June 2022, 12:20 AM
Trying to gather information on relief grinding fixtures - for grinding the likes of countersinks and step drills. Interested in which types other members have used, what they found good/bad, and if it would be practical to make a reasonably functional one (since they aren't readily available and $$$ when they are).
What I've found so far...
There are 2 types of relief that the fixtures can grind. Axial and radial.
Only some fixtures do both.
Axial relief is used for eg countersinks and drills, whereas from what I can work out - radial relief is more for taps??
Example of an axial only fixture is this Harig one:
All the interesting bits are hidden inside, so not sure how it works.
Manual Harig.JPG (https://metalworkforums.com/attachment.php?attachmentid=398964&d=1655379583)
The Weldon Model S I'm pretty sure does both axial and radial relief:
Appears to be a face cam for the axial, but I haven't worked out how the radial happens.
IMG_3829-1333x1000.jpg (https://metalworkforums.com/attachment.php?attachmentid=398966&d=1655379944)
And then there's the Royal Oak style which does both axial and radial:
This is BC's (SteamLoco1954) that he's posted about previously.
I understand that the radial cam moves the link arm to move the spindle forward and produce axial relief.
Not sure about how radial relief works
SAM_0564.jpg (https://metalworkforums.com/attachment.php?attachmentid=398969&d=1655380250)
SAM_0565.jpg (https://metalworkforums.com/attachment.php?attachmentid=398970&d=1655380276)
Finally the generic Chinese 50K drill grinding fixture that only does axial relief - readily available from Aliexpress for around $1K delivered.
From what I can figure out it uses a face cam and pins on the back of the chuck as followers
50K drill grinding fixture.JPG (https://metalworkforums.com/attachment.php?attachmentid=398971&d=1655380563)
I'm sure there are plenty of others out there, but that gives you the idea.
So there are varying levels of complexity in their construction and adjustability.
What is interesting is that I haven't found any home workshop projects on constructing one.
Either its something that people get around some other way to achieve the same resuilt, or they see it as too hard to build, or just not worth the effort.
A few months ago I had a need for a large (1") diameter 82deg countersink for some UNC screws. Nothing readily available locally so I took a very tired 90deg 2 flute one that I had lying around and did some faceted butchery on it using the old Power T&C grinder to get 82deg.
I produced a functional tool, but it was quite time consuming, removed a lot more tool material than was necessary, and was definitely ugly.
Correct me if I'm wrong - but an axial relief grinding fixture would have been the right tool to produce that countersink ??
I've never used one, and all I know about them has come from online sources so fill me in on what I've got wrong or don't know!!
Pros and cons of different types, your experience using them, what you would consider the idea style or functions, would you attempt to build one or just hack up a crude alternative to get buy while waiting to buy a real one....etc
Steve
Attached Images
https://metalworkforums.com/images/attach/jpg.gif Manual Harig.JPG (https://metalworkforums.com/attachment.php?attachmentid=398964&d=1655379583) (26.6 KB)
https://metalworkforums.com/images/attach/jpg.gif 13.jpg (https://metalworkforums.com/attachment.php?attachmentid=398965&d=1655379753) (230.0 KB)
https://metalworkforums.com/images/attach/jpg.gif IMG_3829-1333x1000.jpg (https://metalworkforums.com/attachment.php?attachmentid=398966&d=1655379944) (204.9 KB)
https://metalworkforums.com/images/attach/jpg.gif SAM_0564.jpg (https://metalworkforums.com/attachment.php?attachmentid=398969&d=1655380250) (146.2 KB)
https://metalworkforums.com/images/attach/jpg.gif SAM_0565.jpg (https://metalworkforums.com/attachment.php?attachmentid=398970&d=1655380276) (171.5 KB)
https://metalworkforums.com/images/attach/jpg.gif 50K drill grinding fixture.JPG (https://metalworkforums.com/attachment.php?attachmentid=398971&d=1655380563) (25.1 KB)
Read the full thread at metalworkforums.com... (https://metalworkforums.com/showthread.php?t=208245&goto=newpost)
What I've found so far...
There are 2 types of relief that the fixtures can grind. Axial and radial.
Only some fixtures do both.
Axial relief is used for eg countersinks and drills, whereas from what I can work out - radial relief is more for taps??
Example of an axial only fixture is this Harig one:
All the interesting bits are hidden inside, so not sure how it works.
Manual Harig.JPG (https://metalworkforums.com/attachment.php?attachmentid=398964&d=1655379583)
The Weldon Model S I'm pretty sure does both axial and radial relief:
Appears to be a face cam for the axial, but I haven't worked out how the radial happens.
IMG_3829-1333x1000.jpg (https://metalworkforums.com/attachment.php?attachmentid=398966&d=1655379944)
And then there's the Royal Oak style which does both axial and radial:
This is BC's (SteamLoco1954) that he's posted about previously.
I understand that the radial cam moves the link arm to move the spindle forward and produce axial relief.
Not sure about how radial relief works
SAM_0564.jpg (https://metalworkforums.com/attachment.php?attachmentid=398969&d=1655380250)
SAM_0565.jpg (https://metalworkforums.com/attachment.php?attachmentid=398970&d=1655380276)
Finally the generic Chinese 50K drill grinding fixture that only does axial relief - readily available from Aliexpress for around $1K delivered.
From what I can figure out it uses a face cam and pins on the back of the chuck as followers
50K drill grinding fixture.JPG (https://metalworkforums.com/attachment.php?attachmentid=398971&d=1655380563)
I'm sure there are plenty of others out there, but that gives you the idea.
So there are varying levels of complexity in their construction and adjustability.
What is interesting is that I haven't found any home workshop projects on constructing one.
Either its something that people get around some other way to achieve the same resuilt, or they see it as too hard to build, or just not worth the effort.
A few months ago I had a need for a large (1") diameter 82deg countersink for some UNC screws. Nothing readily available locally so I took a very tired 90deg 2 flute one that I had lying around and did some faceted butchery on it using the old Power T&C grinder to get 82deg.
I produced a functional tool, but it was quite time consuming, removed a lot more tool material than was necessary, and was definitely ugly.
Correct me if I'm wrong - but an axial relief grinding fixture would have been the right tool to produce that countersink ??
I've never used one, and all I know about them has come from online sources so fill me in on what I've got wrong or don't know!!
Pros and cons of different types, your experience using them, what you would consider the idea style or functions, would you attempt to build one or just hack up a crude alternative to get buy while waiting to buy a real one....etc
Steve
Attached Images
https://metalworkforums.com/images/attach/jpg.gif Manual Harig.JPG (https://metalworkforums.com/attachment.php?attachmentid=398964&d=1655379583) (26.6 KB)
https://metalworkforums.com/images/attach/jpg.gif 13.jpg (https://metalworkforums.com/attachment.php?attachmentid=398965&d=1655379753) (230.0 KB)
https://metalworkforums.com/images/attach/jpg.gif IMG_3829-1333x1000.jpg (https://metalworkforums.com/attachment.php?attachmentid=398966&d=1655379944) (204.9 KB)
https://metalworkforums.com/images/attach/jpg.gif SAM_0564.jpg (https://metalworkforums.com/attachment.php?attachmentid=398969&d=1655380250) (146.2 KB)
https://metalworkforums.com/images/attach/jpg.gif SAM_0565.jpg (https://metalworkforums.com/attachment.php?attachmentid=398970&d=1655380276) (171.5 KB)
https://metalworkforums.com/images/attach/jpg.gif 50K drill grinding fixture.JPG (https://metalworkforums.com/attachment.php?attachmentid=398971&d=1655380563) (25.1 KB)
Read the full thread at metalworkforums.com... (https://metalworkforums.com/showthread.php?t=208245&goto=newpost)