Help me make a quick change tool post decision please

[seanreit]

I am currently using this: http://www.littlemachineshop.com/pro...ory=-419988835

There is not enough rigidity in it. When I cut titanium, it pushes off and moves around.

I am thinking about these options, if there are others that are better, please help me, especially if the price is better.

http://www.grizzly.com/products/g5689

http://www.littlemachineshop.com/pro...ory=-419988835

http://www.grizzly.com/products/Quic...14-Swing/G5690

It is for this:

[TOTALLYRC]

The last one be listed is much taller and bigger, so while it may flex less, it might be to tall to fit the machine properly.

Looking at the picture, the way that you built the new carriage, it is more than likely the cause of the flex. If I am correct, you have a linear bearing on each side of the bed and the new carriage stradles the bed, kind of looks like a square C with the opening pointing down. Plus it is made of aluminum. All it has to do is flex a half a thou when doing hard materials and it will give a poor cut. On top of that, the aluminum won't dampen the vibrations like cast iron will do to the properties of each material.

Mike.

[seanreit]

Mike thanks for the input, I'm not getting any noticeable flex that is showing up in the finish, what I am getting is push off on the bit, the whole cutting head is moving to the right as it comes into the material. It's rotating, no matter how hard I mash down on the screw to hold the toolchanger to the aluminum plates I made. I was hoping something beefier would allow less movement. At least at this point, this is the weekpoint in the system. The build has gone through multiple revisions, and what you see is not the latest, but provided as rough idea of what I'm trying to accomplish. While I agree aluminum is not optimal, it certainly was easy and cheap to make. I can cut aluminum at 20 thou per pass at 30 IPM and then run two 10 thou finish passes and my parts come out fairly nice. My other machine is a Tormach, so I do understand the advantages of cast iron.

[TOTALLYRC]

If the tool post is rotating around its central mounting point, you have a mounting problem, not a rigidity problem. Normally, if you put enough pressure to rotate the whole qctp, you would snap/chip the cutter.

I would check to make sure that you don't have something weird going on, such as the central bolt bottoming out. The other option to try, just for giggles, would be a piece of drywall sanding screen or similar material to provide a solid grip between the base of the qctp and the cross slide. I am not sure I would leave it that way, but it would be nice to try. I use this on my model airplanes to provide better grip between the propeler and the smooth aluminum mounting hub.

Mike

[seanreit]

Mike, I'm into RC Jets, I will go give your suggestion a try, and thanks for the input.

[TOTALLYRC]

I am into rc everything, almost, but I have taken time off from flying to get the workshop in order.
Please let me know how it works out.

Mike

[LeeWay]

Here is a build I just got going.
http://www.cnczone.com/forums/showthread.php?t=59421
I bought the Phase II from Enco and got free shipping. It is this one.
http://www.use-enco.com/CGI/INSRIT?P...PMAKA=505-2253

It's pretty decent. I had the smaller aluminum one as well. It actually did wiggle and fidget. It just ain't up to any heavy duty stuff. Aluminum is a dead giveaway.

[life3970]

Great job on converting the lathe. Whats your accuracy and speeds\feeds?

Question:
The top plate looks a little thin? I assume you counter bored the top plate to sink the head of the bolt holding your qctp? Being aluminum and thin in that area, you could get flex\pushoff? Also, have you verified all your bolts are tight? If you have any stripped out\bottomed out bolt holes it might cause an issue.

Great job

[RMDMARINE]

I found the piston type QCTP has more movement than the wedge type.
I use a wedge type unit but I stop the right hand movement by drilling and reaming a 1/4 in hole in the tool post and matched the sadle and used a 1/4 in dowel pin to lock the post in place and tightened the main bolt.

To transfer the dowel pin position I machined a point on a peice of 1/4" steel rod just long enough to when it is inserted the point was about .010 lower than the base of the main post. I then scribed a circle for future pins, that is if I want to angle the post other than square to the center line of the lathe.

For the standard position I squared the post and lightly transfered the center of the dowel pin, do not hit it too hard or you will have trouble removing the transfer pin.

ALORIS QCTP installs the reamed hole on all of their tool post and gives you the transfer pin. I did this on my Southbend 17" turnado and hog off .250 on a side in 416 S/S with no movement.

RMD

[nodaker]

If you are using a 12" swing lathe which is what your harbor freight lathe looks like, a 200 series or bxa would probably be about right. the 100 series or axa is for a smaller lathe.

I have a 12" swing grizzly lathe (G4003G) gunsmith lather and it came with a 200 series system.

You might also look at CDCO as they have attrative pricing on additional tool holders (I have no interest in them other than as a vendor) I found the tool holders needed new socket head screws as the ones shipped were soft steel and broke when used.

John