Drilling on a lathe problems suggestions ?

[bedangerous]

I have a Jet 1442 lathe with a Nova Chuck and pen jaws. I am having problems getting reliable drilling of my blanks. Despite alignment being good I keep getting a wider flare at the drill entry sit making it difficult for a good tube fit. The drill bit goes in snug without a flare but the flare occurs during drilling. I do not feel any wobble of the tail stock.

In addition I keep getting heat build up and smoking blanks. I have tried drilling at 4-500 and faster speeds and it does not seem to make a difference.

Any suggestions.
Thanks,
Mitch

 

[Joe S.]

I would try lowering your feed rate (how fast the drill bit is going in), and be careful when the bit comes out when you clean the chips out.

 

[anthonyd]

Use a center drill to start a pilot hole. This helps the drill start straight and not wander. Sharp drill bits are a must. Also use some water to cool the bit down when drilling acrylic. I also agree with Joe. You have to alter your feed rate and only drill a short section at a time in order to clear the hole of debris and allow the bit and material to cool.

Tony

 

[mremington]

I was having this exact same problem when using brad-point bits like the ones sold by many pen suppliers. The points were picking their own entry point and the bit was flexing as it drilled. I solved it by getting a shorter bit without the brad point. It solved the flare but no the heat. For the heat I just take my time drilling and hit the bit with compressed air to cool it off.

This is the 7mm bit I got:

Amazon.com: CTD Metric Magnum Super Premium 7mm Drill Bit (2 Pack): Automotive

 

[shastastan]

I was having this exact same problem when using brad-point bits like the ones sold by many pen suppliers. The points were picking their own entry point and the bit was flexing as it drilled. I solved it by getting a shorter bit without the brad point. It solved the flare but no the heat. For the heat I just take my time drilling and hit the bit with compressed air to cool it off.

This is the 7mm bit I got:

Amazon.com: CTD Metric Magnum Super Premium 7mm Drill Bit (2 Pack): Automotive

Thanks. I just ordered. I have some longer bits and for me, the longer the bit, the bigger chance of movement. That's one reason I stopped using my Delta drill press. I'm still working on trying to get rid of the run out on the dp. Since I switched to using the lathe, the results are much better. The kind of wood also makes a difference on the burning. I use a slow speed and back out the chips a few times. YMMV

 

[thewishman]

Are the bits sharp? That makes a huge difference.

 

[monophoto]

I have a theory about that.

I've been making 'cheap pens' (aka '12 cent pens'), and have observed that

• If I hold the blank in a chuck in the headstock, and feed a stationary bit into the end from a Jacobs chuck in the tailstock, the hole is oversized near it's entry point - every time.
• But if I put the Jacobs chuck in the headstock and advance the blank into the bit, the entry hole is almost always the nominal size of the bit.

I think the explanation for this is runout. If you mount a blank in a chuck, you will get maximum runout at the end of the blank - which is also where the bit enters the blank. Therefore, that runout causes the bit to bore an entry hole that is slightly larger than the bit, but the hole will taper down to exactly the diameter of the bit as the bit advances further into the blank where there is less runout.

But if you turn things around and have the bit mounted in the headstock, the maximum runout will be at the tip of the bit. Now, when you push the blank onto the bit, the bit creates a hole at the point where it enters the blank that is the size of the bit, but as the blank advances onto the bit, the runout at the tip of the bit causes the hole to expand outward the further in you go - but with the size of the entry hold not changing.

 

[flyitfast]

Use a center drill to start a pilot hole. This helps the drill start straight and not wander. Sharp drill bits are a must. Also use some water to cool the bit down when drilling acrylic. I also agree with Joe. You have to alter your feed rate and only drill a short section at a time in order to clear the hole of debris and allow the bit and material to cool.

Tony

All Tony's above comments and make sure your quill lock isn't too loose. I have found that if it is too loose I get the flare you are talking about. Not too tight or the quill won't move!
The center bit that Tony talks about has really been a success for me when lathe drilling.
Also, keep your right hand on the drill chuck to keep the taper secure in the tailstock. Your hand helps to guide the drill bit back into the hole if you back it out to clear chips.
gordon

 

[Mias]

Thank you for this, I will try this.

mias

 

[Indiana_Parrothead]

A lot of good ideas and suggestions here. You can pretty well tell if you bits are not sharp by the shape of the chips coming off the bit. If it is almost like a powder you are way past needing sharp bits. The smaller the chips the duller the bit. With a sharp bit on acyrilcs you should have corkscrews coming out. Wood is a little bit tougher to tell depending on the species being drilled, but it should be chips and not dust.

Mike

 

[Jim Burr]

Brad points are a bad bit for drilling pens. They have a history wandering through the blank following soft grain patterns. Sharp jobber bit is your best bet.

 

[Dan Masshardt]

Interesting.

I use mostly brad point bits and gave not had any problems in any material.

The biggest drawback of brad points from my perspective is that the can't be sharpened.

For that reason, dull bits seem a likely culprit to me. Try and brand new bit.

Also I always make sure the end of the blank is squared off before drilling begins.

 

[Dale Allen]

Here's a way to check to see if it is runout on the headstock or an alignment problem.
Note: this requires the use of a live center and a spur or dead center.
Take a ho-hum square blank 5" long and find the center of each end.
Drill both with a small bit, preferably a center bit.
Now, put it between centers and turn it round to the largest diameter you can and make sure it is the same diameter all the way along. Before removing it from the lathe, part it in the middle.
Next, put one of the halves in your scroll chuck or whatever you use to hold a blank for drilling with the center hole pointing toward the tailstock.
BEFORE you drill. make sure the blank spins at dead center, meaning there is no wobble at the end when the lathe is running. I use a dial indicator for this but it is not absolutely necessary. What is most important is that the end of the round blank spins at true center.
If you cannot get it to spin dead center then I'd say at this point the problem is too much runout in the headstock drive and you will never get a good drill hole.

If you do get it to spin with no wobble, drill it as you would with a square blank and see of the entry hole is still oversize.
If it is then the centers are either not aligned or the through plane from end to end is out of alignment.
This is how I drill all of my blanks.
It takes extra time but is most accurate.

And BTW, I agree about not using the brad bits. I only use quality jobber bits that are the same angle that are used for steel.

 

[bedangerous]

I have a Nova 3 chuck and actually I realized today that I had not fully screwed in the insert adapter for the 8 TPI adapter. After screwing it in fully it drilled true. Hopefully this was the problem. I have brand new sharp set of Brad bits.
Thanks,
Mitch