I have a 4" Craftsman lathe. One of the very old ones. It worked fine for years and then I decided to "improve" it. You guys know this one. It works fine so I will not leave it alone! Started with taking the spindle out and "cleaning" it. That is when the chatter started. Had a new feed screw nut made for the carriage, the thing that looks like a top hat with reverse threads. Wanted to take out the back and forth play. No Help. Took the spindle out and had a new tail bushing made out of oil bronze. No change. Bought a live center, ditto. The front spindle bushing is a bronze collet. You can tighten it to put more or less pressure on the spindle. My thought, right now, is that it may be too tight. When the tool pushes against the steel, it may need to have some give. Sounds backward but I have tried everything else including several bits. Remember, this is a hobby lathe.Thoughts?
Craftsman 4" Lathe Chatter
- Thread starter centershot
- Start date
carlsbad
Lions don't lose sleep over the opinions of sheep.
Keep it simple. Very seldom does something that seems backwards turn out to be backwards. I'm not familiar with this spindle but chatter means not stiff enough or not tight. If you're tried everything, then dissemble again and reassemble slowly looking for something you missed. --Jerry
Check cross feed Gibbs , is your tail center aligned with chuck center ?
That is a pretty large chunk of steel to be using with 1/4 ?
Less over hang on your cutting tool ?
Just looked at the tool post again. Looks larger than 1/4 but the over hang is a bit much . Try changing you angle and reduce overhang .
That is a pretty large chunk of steel to be using with 1/4 ?
Less over hang on your cutting tool ?
Just looked at the tool post again. Looks larger than 1/4 but the over hang is a bit much . Try changing you angle and reduce overhang .
hogpatrol
Gold $$ Contributor
This ^^^^. "had a new tail bushing made out of oil bronze". Was that the original material? Check the new tail bushing. Was it lubricated on the install? It may have worn out already or been made with too much clearance. With the info given, all fingers point to the new bushing.
hpshooter
Gold $$ Contributor
Did this same set up (tool, overhang of the tool, material speed and feed depth of cut etc.) cut chatter free before the cleaning was done? If it did my comments may not apply.
Looking at the pictures of the tool would prompt me to check the tool geometry with regard to the center line of the work piece and the relief and cleareance angles of the tool. Also, it appears that there is a 90 degree corner on the leading edge of the cutter. The tip of the tool for straight turning generally is placed on the centerline of the work piece and for roughing that size tool often works best with a 1/64 or so radius on the cutting edge.
The other thing is that it appears that there is a lot of unsupported tool hanging out of the tool post. Do you have a tool holder for the tool post? A tool holder used in conjunction with a rocker in the lantern type tool post you have allows you to give a great deal of support to the cutting tool which reduces vibration and, consequently, chatter.
The size and minimum rigidity of these lathes limit them to some pretty light cuts. Excessive overhang and improper tool geometry really shows up on them. My guess is that anything over a .015 cut with the set up pictured would be a challenge on CRS.
Looking at the pictures of the tool would prompt me to check the tool geometry with regard to the center line of the work piece and the relief and cleareance angles of the tool. Also, it appears that there is a 90 degree corner on the leading edge of the cutter. The tip of the tool for straight turning generally is placed on the centerline of the work piece and for roughing that size tool often works best with a 1/64 or so radius on the cutting edge.
The other thing is that it appears that there is a lot of unsupported tool hanging out of the tool post. Do you have a tool holder for the tool post? A tool holder used in conjunction with a rocker in the lantern type tool post you have allows you to give a great deal of support to the cutting tool which reduces vibration and, consequently, chatter.
The size and minimum rigidity of these lathes limit them to some pretty light cuts. Excessive overhang and improper tool geometry really shows up on them. My guess is that anything over a .015 cut with the set up pictured would be a challenge on CRS.
Johnny_V
Silver $$ Contributor
I've been machining for over 40 years, and I can tell you a few things I see that may be wrong. First, the tool bit needs to be better supported (I'm surprised you didn't break the bit with as far as it's overhanging). Second, slower speed (especially with the size material you are trying to machine). Third, make certain the tool bit is sharp and set a few thousands below center. Everything else you stated that's been done sounds like you're good to go.
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Alex Wheeler
Site $$ Sponsor
Pry chuck in, out, up, down. Look for only a few ten thousandths. If that is ok, then its all the basics, tool and part overhang, tool on center with proper angles exc.
Before I took the spindle out the first time, it worked just fine. Even with all of the suggestions that were brought up that did not look right. I could put the old bushing back in the tail of the spindle.
hogpatrol
Gold $$ Contributor
BINGO! Definitely worth trying. Check the i.d. on both too.
shortgrass
Silver $$ Contributor
I keep going back and looking at pic #4. Where's the tool holder that goes with the tool post? Then I click on pic #5. Tool looks to be below center,, alot! That "tool" needs some help, too.
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The chatter also happens with aluminum. As I look back, The chatter started before the bushing was replaced. I replaced the bushing to get rid of the chatter.
A good basic magazine is " the Homeshop Machinist " it covers all aspects of tool set up .
If the chatter continues try deeper cuts . It sounds wrong but if your tool is set correctly and sharp , you could be too fast and too light of a cut .
Good luck
I just enlarged the photos , are you trying to eliminate or cut over the chatter ?
Once the work is that bad about the only way to remove it is with a file ( on such a light machine )
It's very hard to cut the chatter marks out .
One other observation , I don't see ANY lube , anywhere .
Please try to adjust your tool overhang , adjust its height , and let me know if anything worked .
Gary
If the chatter continues try deeper cuts . It sounds wrong but if your tool is set correctly and sharp , you could be too fast and too light of a cut .
Good luck
I just enlarged the photos , are you trying to eliminate or cut over the chatter ?
Once the work is that bad about the only way to remove it is with a file ( on such a light machine )
It's very hard to cut the chatter marks out .
One other observation , I don't see ANY lube , anywhere .
Please try to adjust your tool overhang , adjust its height , and let me know if anything worked .
Gary
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I AM NO MACHINIST, bit is the bit ground right or mounted right for a right hand cut?
I think that what I will do with this is start from the beginning. I will purchase a 1/4" carbon steel bit and see if it works. Does anyone know of a person or business who would sell a right hand bit? Something that is ground with gauges and not free hand.
hpshooter
Gold $$ Contributor
A goggle search for "grinding HSS lathe tools" will provide a lot of information.
www.steves--workshop.co.uk/tips/toolgrinding/toolgrinding.htm should take you to a lot of information including a couple simple fixtures for grinding tools.
Pre ground HSS tools are available. I have never purchased any so I can't provide a source but would guess they could be found with a web search.
www.steves--workshop.co.uk/tips/toolgrinding/toolgrinding.htm should take you to a lot of information including a couple simple fixtures for grinding tools.
Pre ground HSS tools are available. I have never purchased any so I can't provide a source but would guess they could be found with a web search.
Alex Wheeler
Site $$ Sponsor
The angles are not that critical... Get rid of the top rake. Grind clearence on the left side and front of the tool. Knock the corner off a little. leave the top alone. Set it on center and the bit level, you may need a spacer under it.
hogpatrol
Gold $$ Contributor
A green wheel and tool selection will fix the problem . Larry
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