Does a short 3 flute carbide bit drill a straight hole?
- Thread starter JC
- Start date
JC
Coos Cues
I'm talking about the 3 flute carbide drill bits, not end mills. I have some and they seem to drill an extremely nice hole in wood if you center drill first. I'm not sure boring will make a noticeable improvement whether with an end mill or just a boring bar. But I may be wrong. Just wonder what other's experience is with this type of drill bit and wood.
JC
Sometimes...
Drill bits drill holes that are somewhat oblong, to get them round you need to use a reamer.
To get a "perfectly" sized, round, straight-down-the-centerline hole you need to drill
an undersized hole and finish with a boring bar... if you expect to provide parts for NASA.
Dale
The most solid drills, are those with the most amount of material. Like early 2 and 3 flute Carbide drills. The 3 flute drills work well, but I would not trust any drill to drill wood and expect it to be straight. Drilling and then leaving a small amount, 0.5mm on diameter 0.020 inches on diameter and then a bore bar is the way to go. If you have live tooling, you could send an endmill down and then use a non even pitch fluted reamer to make very round and fairly straight holes. Again if you leave too much for the reamer, then the wood grain will influence the reamer, even if it is carbide. In wood often the wood will move if it is outside of the collet/chuck by any appreciable amount. Also Carbide is actually quite flexible, but not as bad as HSS. It can be scary seeing carbide tooling moving /flexing. For pins, I drill and bore using my drill/bore tool. By the time you set up and centre , drill, bore, it is just easier and for me quicker to use the one tool for all three operations. Using taps with a guide diameter also helps when it comes to pin installation, or in your case, live threading will make for a great concentric thread.
Maybe it's just me but I've never trusted just drilling. I undesize then bore.
Joint pins? The best advice has already been given, undersize the drill bit and then bore to perfection, hats off for those who already said this.
I use Cobalt steel bits, about the best bits we can buy. (Please don't confuse them with the brand name of Cobalt you would find at Home Depot.) Cobalt steel is the next step beyond Carbide.
The best bits on the strongest machines will still wobble in wood.
I buy my bits at Industrial Welding Supply here in Salem Are-We-Gone, they are online with great products, maybe you have one near you.
Thanks, Dave.
What Mike said :thumbup::thumbup:
Semi hijack but well within the spirit of the OPs question:
Neil, do you have any experience with the good old "D" drill bit... a short length of drill rod
ground flat to a semi-circle cross section. A short starter hole is advised.
Would you think this would be "straighter than drill-and-ream?
Dale
Hi Dale, in my experience the "D" drill is great for wood and non ferrous metals. It is my experience with "D" bits and "D" drills, that is the drill bore tool I make. I find that the D drill is better than a drill and ream. I still think the best is to Drill and bore, but drill with a D drill or a similar tool like the drill bore tool. Boring a hole creates a new hole centre, where as a reamer essentially just follows the existing hole. In wood with uneven grain or uneven densities, reamers can move off the centre of the hole and make a non straight hole. Boring is less effected by the varying density, especially when it is sharp. With "D" drills, in my experience if you are careful as it is started, it will start concentric and make a straight hole to within about 1 thou in diameter of the drill rod stock. It is Important in my experience that the "D" is cut exactly to the centre line or above the centre line by 0.01mm or 4/10 thou inches. For the drill, it can be a similar point angle to a regular drill, but I think the 140deg point angle is better. Again the, angle face and back off, wants to be concentric to within 0.01mm of it's true centre line. If it's cut too far over, it will cut over size,and then the body of the drill does not offer support and alignment. Interestingly, if the grind is off centre, it seems to drill oversize as well. Another point option is that of a Gun drill where the drill angle is cut for 25% of the hole diameter and then the same angle going right back. The outer area and the inner area plus the centre cut, keep it in an even load situation. It is also self guided to a certain degree.
Neil
Chris, Thanks for that tip a few years back.............. I have installed all my pins by drilling the hole with a 3 flute carbide drill........... no need to bore...........
Kim
also.run an experiment
If I want to know if a tool will do the job I would just test it.
Naturally if I can afford it too. In this case I would use some scrap
wild grain wood and see if I can drill and install a pin. If the pin is
centered and straight then I would say it works. Then go for it.
Until you find something easier.
Hopefully what you are doing is making you happy.
If I want to know if a tool will do the job I would just test it.
Naturally if I can afford it too. In this case I would use some scrap
wild grain wood and see if I can drill and install a pin. If the pin is
centered and straight then I would say it works. Then go for it.
Until you find something easier.
Hopefully what you are doing is making you happy.
I forgot to list my method
I drilled and bored to install pins and inserts.
I have a drill and boring bar mounted on my
tooling post so it is relatively quick. But I do use
drill bits, end mills, boring bars to make holes.
My drill bits are cheap or average cost but I
sharpen them with a Black Diamond sharpener .
118 degree tips seem to wander more than the
135 degree split point style.
Hope this helps.
I drilled and bored to install pins and inserts.
I have a drill and boring bar mounted on my
tooling post so it is relatively quick. But I do use
drill bits, end mills, boring bars to make holes.
My drill bits are cheap or average cost but I
sharpen them with a Black Diamond sharpener .
118 degree tips seem to wander more than the
135 degree split point style.
Hope this helps.
Because the 118 has a thick web which puts much more force on the drill.
The 135 split point drills much freer at the point.
JC
Coos Cues
@ $40-80 a bit I thought it would be wisest to ask those who had already tested it for me and see what the consensus is.
Of course someone will scold me any time now and inform me that this is not a forum to teach me how to build cues, but what can I do? I can't help myself I'm just moochy by nature.
Thanks to everyone for sharing your experiences.:smile:
JC
Carbide offers two advantages over high speed steel it is more rigid and it is harder so it will retain a cutting edge longer. In our case the real advantage is the wood grain wont push the drill off center. So if your drill doesnt move then all you have to worry about is the wood moving . If your work is held rigid then you have minimized a lot of inacuracy in drilling holes. In my case when doing joint work I hold the cue in a collet system and minimize the amount hanging out in front of the collet. Using a boring bar is more about hitting an exact size because drilling doesnt give you a perfectly round hole.
Last edited: