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I'm using a 90 spot
I follow the same rules when it comes to 90 spots. I didn't think about it walking on the bigger drills center. Thanks for the suggestion.You need to spot the bottom of the 35/64 hole. The 3/8 drill is walking on the dead center of the bigger drill.
FWIW, although it's common wisdom that the spot angle is > the drill angle. I don't have trouble with 90 spots and hss drills. I do follow the rule for carbide.
In order of hole alignment accuracy, from least to best, its:Tried drilling with both spindles turning. In my opinion i don't think this will help you. Drilling with only the turning spindle worked always the best in my cases.
In order of hole alignment accuracy, from least to best, its:
1. Workpiece stationary, drill rotating
2. Workpiece rotating, drill stationary.
3. Workpiece and drill counter rotating
The above is tried and true over many decades and not just a hypothesis. Point 2 above is often demonstrated on lathes where the centre line of the tool holder, and hence the drill, is slightly off to that of the rotating spindle. In practice and within reason, the point of the drill will be pulled into alignment with the axis of the spindle.
Many machines that have live tooling don't allow the main spindle to be rotating under normal turning conditions and the live tool at the same time. Rotating the spindle as a "C" axis would be doable, but the max speed wouldn't be well suited to small diameter tools. However, if the OP's machine is capable, it will be easy for him to implement, and there are no negatives in doing so.
Regards,
Bill
I remember reading this in the Guhring catalog. I believe they said when spotting with a 90 degree center for a HSS drill to create a spot that is 70% of the diameter of the drilled hole. That's what I've been doing and have had good success.Years ago a Guhring catalog said spot with a larger angle for carbide (usually 142 v 140 for me) and smaller angle for HSS (90 v 118.) So assuming your 118 drill is HSS please try spotting to maybe 3/16” diameter, then drilling, then coming back to chamfer and see if it helps. Good luck!
Mazak makes this super easy and it was my first time trying it out. It asks for the spindle RPM and then whatever is left over to match your entered SFM is what speed the live tool runs at.Many machines that have live tooling don't allow the main spindle to be rotating under normal turning conditions and the live tool at the same time. Rotating the spindle as a "C" axis would be doable, but the max speed wouldn't be well suited to small diameter tools, but the RPM combination of the two counter rotating spindles will achieve the correct surface speed for the drill being used. However, if the OP's machine is capable, it will be easy for him to implement, and there are no negatives in doing so.
Regards,
Bill
Thanks for this suggestion Ox, I did try jogging it in and out of the hole (giggity) but did not see any flex or movement in the drill. I will add this method to the ole brain bank for future use however.But first, have you jogged your drill in and out of the hole after it is done?
Doo you see any movement in the drill tip in any direction?
Put your finger on it - can you feel it it the part as it enters the hole?
You need to doo this fast enough that you will see and feel the movement, likely NOT at .001 on the MPG.
Use .01 or just the JOG button.
If you are out of location and have a stiff holder, this SHOULD show up as a tapered hole that the trailing flutes are rubbing on, and not exactly show up as a out of center exit, but ... (???)
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I am Ox and I approve this post!
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