All Replies on Hollowing logs

chain saw

what is the diameter of the hole you would like to have ?
will it have the same size hole in all the logs ?
or – will the thickness of the log dictate how big the hole will be.
will the hole go all the way through to make it completely hollow ?

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-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

Thank you for your quick feedback!

A Chainsaw is not an option unfortunately since u won`t be able to make clean holes. I already have a way to hollow the logs but with this current method it is not possible to make it clean. Since i want to sell the products, i need a more efficient and “better looking” way to make to holes.

what is the diameter of the hole you would like to have ?
will it have the same size hole in all the logs ?
will the hole go all the way through to make it completely hollow ?

The diameter of the holes are ranging between 4,7 inches (12 cm) and 2,7 inches (7cm). So yes, I am planning on making different diameters for different log sizes.

It will depend on the product, some should be completely hollow and some only half.

Arthropod

In my experience, Forstner bits don’t play well with end grain. Twist drills do much better. I would probably use a large twist drill to rough it out then use a bowl gouge or carbide tool to finish it to the final diameter.

-- Kenny, SW VA, Go Hokies!!!

just out of curiosity – what will the logs be used for once
you have found a way to process them ?

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-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

In my experience, Forstner bits don t play well with end grain. Twist drills do much better. I would probably use a large twist drill to rough it out then use a bowl gouge or carbide tool to finish it to the final diameter.

Yes, that`s what i thought. But do you think not even a metal lathe, with a lot of precision and control can do the job?
I have been using twist drills up until now by drilling a circle then hammering out the core. After that i finished it with a gouge like you mentioned. Unfortunately tho, by doing this the hole is very rough and i need it to be perfectly round and smooth. Furthermore this work is very exhausting and not doable on a medium scale in the long run.

just out of curiosity – what will the logs be used for once
you have found a way to process them ?

For now I am using them for lanterns and nesting aids for insects. I am living in central Europe and they are getting more and more popular here.
But my plans are to make even more as i go.

hmmmmm – - – I googled “insect nesting aids” and now I understand.
I saw something like that on a Nature TV show a while back . . . .
here in Central Florida, we just leave the garage door open for a day or two. (joke).
best of luck in your projects – not too many people realize just how important
the beneficial insects are to our own ecosystem. without the proper pollination,
we could very well starve to death in less than a century.
~but~ I don’t see any examples of insect nesting boxes that are perfectly smooth
and cylindrical on the inside (other than a pipe filled with straws or bamboo) – - – -
maybe you are overthinking your design just a little.

I APPLAUD YOUR EFFORTS !!!

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-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

You aren’t going to be able to find a Forstner bit big enough to drill out a 4.7” diameter log on the lathe. You would have to drill multiple holes on the drill press and hog out the rest somehow. To use the wood lathe, you could drill a single hole in the middle and then use a hollowing tool to remove the rest, working in from both ends. With the 8” length, you will need a pretty long tool to safely reach halfway in from each end. (If I remember correctly the rule of thumb is 1 to 5 ratio of length past the tool rest to behind it.) A tool like the D-Way hollowing tool would give you a long enough reach. Sorby may make something similar and I’ve seen some homemade versions of that tool online as well. You will need a chuck to mount the logs on the lathe.

I’ve never tried it but I wonder if you would be able to use a bandsaw to do that, sort of like making a bandsaw box. You would make an entry cut and cut a circle around the inside and exit in the same place you entered? Might be a challenge with an 8” piece.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

Lazyman’s technique does require sawing in from a side, but after the center is out, you can cut off an end of the removed piece (for one that doesn’t go all the way through), and glue it back in, plus glue where the cut entered from the side. As he says, this is how bandsaw boxes are made.

Another thought: if you tilted the bandsaw table slightly, your center plug would be tapered, and would fit tightly if pushed through. (I realize that’s not very clear, but best I can do right now). In Belize, we watched a drum maker make a series of nesting drums this way.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

hmmmmm – - – I googled “insect nesting aids” and now I understand.
I saw something like that on a Nature TV show a while back . . . .
here in Central Florida, we just leave the garage door open for a day or two. (joke).
best of luck in your projects – not too many people realize just how important
the beneficial insects are to our own ecosystem. without the proper pollination,
we could very well starve to death in less than a century.
~but~ I don t see any examples of insect nesting boxes that are perfectly smooth
and cylindrical on the inside (other than a pipe filled with straws or bamboo) – - – -
maybe you are overthinking your design just a little.

I APPLAUD YOUR EFFORTS !!!

Well thank you John!
But the nesting boxes you described is exactly what I am doing. I fill the Pipe with bamboo and drill holes in the outer ring. I already sold some “prototypes” on a market and was pretty successful doing so. This is why I want to perfect the product and why I`m not too shy about investing some money.

You aren t going to be able to find a Forstner bit big enough to drill out a 4.7” diameter log on the lathe. You would have to drill multiple holes on the drill press and hog out the rest somehow. To use the wood lathe, you could drill a single hole in the middle and then use a hollowing tool to remove the rest, working in from both ends. With the 8” length, you will need a pretty long tool to safely reach halfway in from each end. (If I remember correctly the rule of thumb is 1 to 5 ratio of length past the tool rest to behind it.) A tool like the D-Way hollowing tool would give you a long enough reach. Sorby may make something similar and I ve seen some homemade versions of that tool online as well. You will need a chuck to mount the logs on the lathe.

Thank you for your feedback Lazyman!
I actually found a forstnerbit this big on the internet and I originally planned on making multiple drills and using a bigger bit each round.
But you actually brought up another idea in me! What if I use a metal lathe and drill a first small hole (2 inches) in the middle with a twist drill. After that i use a long wood turning tool, mount it on the cross slide of the lathe and increase the diameter a bit more each round?

I ve never tried it but I wonder if you would be able to use a bandsaw to do that, sort of like making a bandsaw box. You would make an entry cut and cut a circle around the inside and exit in the same place you entered? Might be a challenge with an 8” piece.

Lazyman s technique does require sawing in from a side, but after the center is out, you can cut off an end of the removed piece (for one that doesn t go all the way through), and glue it back in, plus glue where the cut entered from the side. As he says, this is how bandsaw boxes are made.

Another thought: if you tilted the bandsaw table slightly, your center plug would be tapered, and would fit tightly if pushed through. (I realize that s not very clear, but best I can do right now). In Belize, we watched a drum maker make a series of nesting drums this way.

I thought about this idea myself a lot but I am not a huge fan of cutting up the log and then gluing/screwing it back together. If there is no other way, I will probably go for this method but until then I am searching for other ways.

Thank you for your input tho!

yes it could be done on a metal lathe with a boring bar, or a wood lathe with a hollowing tool. Either would use the same cutting tool, a small dia carbide or square 3/16” hss bit. Depends on what you have access to or $ you want to spend. Either would use a drilled hole to get started. For a wood lathe look for a captured hollowing tool, not a free hand type. I like Lyle Jamieson’s design, but there are many, including articulating. Either metal or wood lathe can leave a decent surface finish. My have to clean up with a scraper and a little sandpaper – dont know just how smooth you want it. Provide more details of tool access and finished product description.

yes it could be done on a metal lathe with a boring bar, or a wood lathe with a hollowing tool. Either would use the same cutting tool, a small dia carbide or square 3/16” hss bit. Depends on what you have access to or $ you want to spend. Either would use a drilled hole to get started. For a wood lathe look for a captured hollowing tool, not a free hand type. I like Lyle Jamieson’s design, but there are many, including articulating. Either metal or wood lathe can leave a decent surface finish. My have to clean up with a scraper and a little sandpaper – dont know just how smooth you want it. Provide more details of tool access and finished product description.

Thank you for your input OSU55!
Could u maybe link me one of each cutting tools as example since there is a lot of stuff out there and I am completely new to wood turning. Wouldn`t you say a methal lathe would be better suited since you can easily mount the boaring bar on the cross slide (This one e.g.) which is even self moving?
Since wood lathes are cheaper I would prefer them of course, I`m just not sure how it`s supposed to work without the rails etc.?

Thank you for your feedback Lazyman!
I actually found a forstnerbit this big on the internet and I originally planned on making multiple drills and using a bigger bit each round.
But you actually brought up another idea in me!if I use a metal lathe and drill a first small hole (2 inches) in the middle with a twist drill. After that i use a long wood turning tool, mount it on the cross slide of the lathe and increase the diameter a bit more each round?

- Arthropod

I just did a quick search for 4” forstner bit. Most of the ones I found are intended to be used more like a hole saw in thinner stock for putting a large pipe through a board or drywall. They have 1/4” shafts on them so I would be skeptical that it could handle drilling a 4” deep hole in end grain. I did see one on Grizzly.com that has a 1/2 shaft and carbide cutters that might be beefy enough but it would probably still be a good idea to make multiple passes with successively larger bits and/or drill a more shallow hole.

Your idea to mount a wood turning tool on a metal lathe might work but might be pretty slow going. You will have to make sure that you have the log well mounted in a chuck. If it shifts at all while hollowing you’ll have a problem. Might be a good idea to shorten the log to 6” to make that easier as well as faster to hollow.

Since your goal is to fill it with bamboo to create the nesting tubes here are a few thoughts. First, instead of hollowing and filling with bamboo, why not just drill a honeycomb of holes from each end with an appropriately sized (3/8”?) drill bit. The holes probably only need to be an inch or 2 deep at most but you could go as deep as you want. You could even vary the sizes of the holes to give a more interesting look which might even be better for different types of bugs. This could be easily done on a drill press and maybe even just with a hand drill. This might actually be a more stable design as well. A tube of wood exposed to the elements might crack and fall apart fairly quickly? If you want to stay with the bamboo, then perhaps you could simply hollow out about 2 inches from each end and just insert a bundle of shorter sections of bamboo in from each end. This would be easier than trying to completely hollow the entire 8” log and may result in a more weather stable design. You would need to use some epoxy or maybe even hot glue would work to secure the bamboo bundle.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

You could definitely use a boring bar on a metal lathe. You will probably also need a steady rest having that much length. And, metal lathes have lots of sliding pieces and sleeve bearings and gears and lead screws. They don’t like saw dust so you’ll want to take precautions to shield your headstock, gear box, ways and lead screw and clean it thoroughly after each run.

Here is one option for a boring bar. There are many though.

-- Kenny, SW VA, Go Hokies!!!

Thank you for your feedback Lazyman!
I actually found a forstnerbit this big on the internet and I originally planned on making multiple drills and using a bigger bit each round.
But you actually brought up another idea in me!if I use a metal lathe and drill a first small hole (2 inches) in the middle with a twist drill. After that i use a long wood turning tool, mount it on the cross slide of the lathe and increase the diameter a bit more each round?

- Arthropod

I just did a quick search for 4” forstner bit. Most of the ones I found are intended to be used more like a hole saw in thinner stock for putting a large pipe through a board or drywall. They have 1/4” shafts on them so I would be skeptical that it could handle drilling a 4” deep hole in end grain. I did see one on Grizzly.com that has a 1/2 shaft and carbide cutters that might be beefy enough but it would probably still be a good idea to make multiple passes with successively larger bits and/or drill a more shallow hole.

Your idea to mount a wood turning tool on a metal lathe might work but might be pretty slow going. You will have to make sure that you have the log well mounted in a chuck. If it shifts at all while hollowing you ll have a problem. Might be a good idea to shorten the log to 6” to make that easier as well as faster to hollow.

Since your goal is to fill it with bamboo to create the nesting tubes here are a few thoughts. First, instead of hollowing and filling with bamboo, why not just drill a honeycomb of holes from each end with an appropriately sized (3/8”?) drill bit. The holes probably only need to be an inch or 2 deep at most but you could go as deep as you want. You could even vary the sizes of the holes to give a more interesting look which might even be better for different types of bugs. This could be easily done on a drill press and maybe even just with a hand drill. This might actually be a more stable design as well. A tube of wood exposed to the elements might crack and fall apart fairly quickly? If you want to stay with the bamboo, then perhaps you could simply hollow out about 2 inches from each end and just insert a bundle of shorter sections of bamboo in from each end. This would be easier than trying to completely hollow the entire 8” log and may result in a more weather stable design. You would need to use some epoxy or maybe even hot glue would work to secure the bamboo bundle.

Yes, I pretty much shifted from the idea with the forstner bit since it really doesn`t do well with end grain on such a large scale.

The “honeycomb” idea is problematic since the log (when it`s not hollow) will crack and thereby make the holes unsuitible for insects.
We have had hollow logs with bamboo as nesting boxes for quite a while now and they won`t crack if properly dried. Bamboo is also very durable and I will place them about 0,8 inches inside of the hole so rain can not fall directly on it. You also don`t need to use glue since the bamboo will sit thight if you stuck enough material inside.
I also thought about just hollowing a part of the log but I think this would result in the cracking of the log.

I have produced about 100 of these nesting boxes for now and they work really well. I just need the hole to be clean and precise in order to add some additional features and make it look better. Furthermore, my current way of hollowing the logs is very exhausting and thereby not doable in the long rund.

I appriciate your input tho! :)

For the mounting I am planning on using a metal construction which goes into the chuck and where the log is screwed on (on the outer ring so i won`t get in touch with the screws when turning).

You can buy hole saws 4”+ deep. Run a centre pilot hole then a hole saw in from each end.

Thank you for your input OSU55!
Could u maybe link me one of each cutting tools as example since there is a lot of stuff out there and I am completely new to wood turning. Wouldn`t you say a methal lathe would be better suited since you can easily mount the boaring bar on the cross slide (This one e.g.) which is even self moving?
Since wood lathes are cheaper I would prefer them of course, I`m just not sure how it`s supposed to work without the rails etc.?

- Arthropod

Search for “captured hollowing tool”, and there will be many choices. Plenty of videos to show how they work. With a wood lathe, your hands control tool position and feed speed vs a metal lathe where the machine controls the tool. Type of lathe to use depends a lot on the $ you are willing to spend, which is a function of the volume of product you expect to make and sell, and the profit margin.

A captured hollowing tool removes the torque reaction from your hands, eliminating catches and making for smoother cuts, allowing for tighter tolerances. If you need to hold the ID tight, like .010”, a metal lathe is the choice. If more like .050” or more, a wood lathe would do it. Actual material removal for either lathe type will be about the same – the actual cutting tool will be the same.

What is the max OD log you will turn? Sounds like ~6”? A 6” swing wood lathe will probably not have enough motor – you probably need a good 1-1/2 hp motor.

I don’t know what is available in your area of Europe. I’m just trying to give you ideas and concepts to pursue in your area of the world. I have no idea what type of fabrication capabilities you have or what is available. Something specific like this lends itself to custom machine fabrication if you are capable of such. Custom fabbed work holding would be a good idea as well – screws into end grain is not the best. Something that clamps the log OD, and allows a drill and hollowing tool to cut all the way through the log (not switching ends) is best for production. Workholding will need to support the 8” length – a steady rest won’t work since the OD is not perfectly round. The “chuck” needs enough engagement to hold the whole piece.

There are extra deep carbide tipped hole saws, up to ~5” depth. That may work as well.

I thought it all over again and actually a hole saw with a drill press would make the most sense since u dont have the problem of mounting the log on a chuck and there is way less waste material.
So I went to a carpenter yesterday and he had a 5,5 inch hole saw with a big old drill press. We screwed the log on a board which we then clamped on the drill table. At first try, the saw couldnt engage in the wood because of it`s size it was swinging to much. We then made the initial cut with a shorter hole saw in order to hold the bigger one in position. After that it worked perfectly fine.
So now I`m planning on buying a robust drill press with about 1,5 hp to do the job.
Since I won`t be able to cut through the necassary 7 inches i will try to cut the rest with a jigsaw from the other side.

I`m actually pretty happy with this concept, what do you guys think?

Get a long bit the same size as the hole saw pilot and continue the pilot hole through the log. This will allow you to flip it over and use the hole saw from the other end.

I have seen antique hand augers for making wooden pipe, but don’t know where you would find one. Could a heavy ice auger bit be modified for wood?

Arthropod: what do we think ??
PHOTOS of your process and finished project will get you the
most accurate feedback. glad you are on your way to a safe
and successful adventure.

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-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

Get a long bit the same size as the hole saw pilot and continue the pilot hole through the log. This will allow you to flip it over and use the hole saw from the other end.

- RobbieB

Exactly my thought. For production, figure out a method of clamping around the od of the log to hold it – like a split tube clamp. Quick placement and removal. Carbide tipped hole saw. The longer the stroke on the dp the better – less material to remove on 2nd end. Does a bit of offcenter lip in the middle of the hole cause a problem? Even with a guide hole the holes from each end wont line up perfectly. An option is to drill, raise the dp table then drill again from the same end, but thats time during a production process.

You may want to look at picking up a used concrete core bit. According to what I looked up a 5” dia. has about a 14” depth. Used for concrete, one that’s worn out should be hard enough to be cut off and wood cutting teeth ground in.