Drilling Balsa Block

[Scotty Dog]

What kind of bit and speed of it should I use to drill a 18mm hole in a 3" balsa block. I have an idea I want to try. I figure to CA the balsa before drilling , cuz I dont want it all chaffed,splintered,ect, up . If my idea pans out, Ill incorporate it into a build. Thanks .....

[powderburner]

While I can't answer about specifics of the drill bit selection/etc, I can tell you that the rough cut (chafed, splintered, etc, per your description) would not be helped by applying CA. Besides, CA is not likely to penetrate deeply into the wood, and the internal drilling would still be through un-treated balsa.

Instead, your work piece needs to be solidly anchored or clamped down, your drilling tool needs to be SHARP, your waste removal should be aggressive (pull the bit out and clean the hole often, especially if the bit itself is not removing wasted effectively), and then you need to start asking your questions about bit types, feed rates, RPM, etc---

I would recommend the CA after the hole is rough cut, to allow you to clean up the drilled hole to a more precise diameter and smooth the walls. You probably don't want to add all the weight of soaking the entire block with CA.

[mkadams001]

Use an 18mm Forstner Bit.

[jim fustini]

Sandman? Gordy will know.

[sandman]

Use an 18mm Forstner Bit.

Yep, that's the tool to use. 18mm is "close" to 3/4", well, about as close as you can get with a Forstner bit. (0.736" vs 0.75")

Use a drill press! You will tear it up if you use a hand drill...I promise!

Go slow! Use the lowest speed and very light pressure!

Forget the CA, it won't do anything.

Drill the hole about 1/4" to 1/2" deep first with the Forstner bit

Then change drill bits and drill the hole with a 1/2" drill bit to the depth you want...any kind of twist drill it doesn't matter.

Then, finish the hole with the Forstner bit.

Finally, get yourself a small Arkansas sharpening stone. The kind you would use to sharpen small carving tools. They are cheap about $10 but worth it!

Carefully "dress" the Forstner bit.

The secret to any cutting tool is "KEEP IT SHARP"! and go slow!

[Scotty Dog]

Thanks guys for all the info. I talked with a carpenter,actually hes more a cabinet maker, about this idea. His deal was ,as stated here, to have it held down good,drill press, slow and sharp. Im gona give it up! And show you what Im planning on trying to make. I included a pic that got the wheels spinning. Dont know how many cones I can afford to tear-up trying this Anywhoo- Its a BNC 80HD 5"ogive from Semroc .pics tell it pretty good. 4 canted 18s . BT60 linned hole down to junction of motor tubes. Some smaller holes ,not deep,drilled around it for costmetics, ya know-to get the look. The fin I drew in pic is NOT happening.

[Scotty Dog]

couple more pics One thing I allready picked up on is,the junction of the 4 tubes will be larger than a bt60. I could go with 3 or drill in just enough for the 18 mmt tube and then go with smaller holes and eccentric. I better be careful. this may be more of a PLANS thread.

[sandman]

Maybe sorta like this?

[Scotty Dog]

Maybe sorta like this?

I like the fins. COOL! Its close. Dif is, having the motors coming out of the tail.

[Scotty Dog]

Well, I got a new tool and went for it.Came out ok . Not perfect. I should have used a nicer base than that old painted piece of pine. I set the table at 15 deg. Cut a 4x4 block and screwed NC to center of it. The block I made 4x4 cuz the clamp jaws are 4" This way it made it so I just lined up the corners of the clamp with corners of block ,drilled, losen clamp,1/4 turn and drill,repeat till done. That was my jig.Then I roughly laid out 4 holes on end and drilled down thru till I broke thru. I used a nice new irwin 3/4 bit. Then I got playing with a fin idea. Holes need to be cleaned up and I think Ill CA them.

[Scotty Dog]

more pics

[Scotty Dog]

pics

[El Cheapo]

I think thats looks pretty good for a first attempt on something that seems pretty easy to screw up.

[Agent Titan]

That looks really nice! Tell us how it flies (With Pics!)

[dlazarus6660]

Hey Scott,

How'd I miss this one I dunno?
Any progress? Did you bring this to the CMASS launch?

[Scotty Dog]

Ya it flies.Go to Scratch (nc80-4x18 ?)and youll see the pics and vid.No I didnt bring it to Cmass. Wasnt quite sure about its stablity for me to trust it around a crowd. http://www.rocketryforum.com/showthread.php?t=21915

[Pippen]

.

Drill the hole about 1/4" to 1/2" deep first with the Forstner bit

Then change drill bits and drill the hole with a 1/2" drill bit to the depth you want...any kind of twist drill it doesn't matter.

Then, finish the hole with the Forstner bit.

!

What's the reason for the change to the regular drill bit in the middle?

[RandyT0001]

What's the reason for the change to the regular drill bit in the middle?

Changing to a smaller 1/2" bit removes most of the material up the spirals of the bit. Then returning to the fostner bit means your only drilling about 1/8" from the sides making for a cleaner cut.

[Micromeister]

Pretty KEWL Scotty Dog!
Should be a very interesting flight when complete.

[XrayLizard]

lol, Sharp and FAST soft material = faster speeds.

[Scotty Dog]

lol, Sharp and FAST soft material = faster speeds.

LOL= IT WORKED

[sandman]

Changing to a smaller 1/2" bit removes most of the material up the spirals of the bit. Then returning to the fostner bit means your only drilling about 1/8" from the sides making for a cleaner cut.

Yep, that's the reason. Forstner bits make a nice clean hole but balsa does tend to clog them.

Then you wind up burning a hole in the balsa...not a good thing!