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Hand held needle saw

behnt

New member
#24
I have been AWOL for a while... I have been working on the saw though. So this is a little update.

I have been debating a Kickstarter for the tool. Let me know if you would be interested and how much you would pay for one.

For those that use Onshape here are the 3D files so you can 3D print your own:

For the 180 size motor (slot car motor)
https://cad.onshape.com/documents/c...f507ea7eaa26ca8e3a/e/8fb0da8f4c7d521f7cf84578

For the 280 size motor (somewhat standard dc motor)
https://cad.onshape.com/documents/9...c5999326e0dd175161/e/0d2dab8331887e8acecdaf83

NOTES: I'll get on a write up and video tutorial on how to make them soon but for those of you mechanically inclined this may be enough to get started. To get access to the files you will need to sign up to Onshape.com it is TOTALY worth it and free.

1. Motor needs to be 10watt so a 5V 2A motor or a 12V 1A or......
2. Best wire to use on this is piano wire 0.021" diameter you can get this from unwinding a low E string on a guitar
3. Buy a foot pedal and put it inline between the power source and the saw.
4. Right click on a part in Onshape and choose export and input the settings for a STL file of your choice.
5. Buy a tattoo machine tip from here. https://www.amazon.com/Round-Stainl...&sr=1-4&keywords=tattoo+tip+stainless+3r&th=1

Thats all for now. More to come.
 

behnt

New member
#27
I am still working on this and am having issues with the needle cam. I am finding that the heat of the motor softens the PLA cam I am using. I am hitting a wall on where to go from here. I have come up with this as a alternative to the first version here https://cad.onshape.com/documents/9...c5999326e0dd175161/e/0d2dab8331887e8acecdaf83

Do you guys have any suggestions? I have debated this but wonder if there is a flat plate version out there somewhere https://hobbyking.com/en_us/propeller-adapter-collet-type-3mm-1.html?___store=en_us
 

Merv

Well-known member
#29
Any suggestions or comments?
Great idea. Looking forward to a kit.

One question, why not just mod a tattoo machine to work with FB. The tattoo machines I have see just don’t have a stroke that is long enough to cut all the way through the FB. I would think a different flywheel on a tattoo machine could make the stroke longer.
 

jhitesma

Some guy in the desert
Mentor
#30
Was just thinking about this the other day....I have my MPCNC with my own needle cutter so I don't need one...but it is a low cost of entry that could be handy for a lot of people.

The idea I had though was to add something a sewing machine foot as an adjustable depth stop so it could be used for score cuts and marking cuts as well as simple through cuts. Have a couple ideas on how it could be done - but wanted to toss it out there in case someone with more time than me wants to try to make it work ;)
 

Merv

Well-known member
#31
The idea I had though was to add something a sewing machine foot as an adjustable depth stop so it could be used for score cuts and marking cuts as well as simple through cuts.
With the needle saw, I'm thinking about mounting one a flat base and using it like you would a router, just follow the pattern. Depth of cut adjusted by raising or lowering the needle saw, like a plunge router. OR With shims under the flat plate, paper or card stock would allow very fine depth control. If it works you would not need the CNC
 
#32
The problem I have most of the time cutting by hand is keeping the cut perpendicular...

What Jhitesma and Merv are talking about made me think about setting one up like a bandsaw.

Suspend it over a table with a foot pedal controlling a servo to adjust the depth of the cut, and move the board around under it.

BTW, This is my first post so take it easy on me... 😀
 

jhitesma

Some guy in the desert
Mentor
#33
The problem with mounting it on a base and using it like a router (Assuming I understand that correctly - I'm picturing a router table style of setup) is how are you going to follow the pattern (on top of the work) when doing non-through cuts? You can't see the needle since it's not coming all the way out of the work.

I suppose you could setup a laser pointer to indicate the cut point, or rig up some kind of plexiglass guide over the top (which would increase safety as well if you loose a needle) but that starts to sound kind of inelegant.
 

Merv

Well-known member
#34
The problem with mounting it on a base and using it like a router (Assuming I understand that correctly - I'm picturing a router table style of setup) is how are you going to follow the pattern (on top of the work)
No, not like a router table, like a hand held router, on top of work. I'm thinking FB on bottom, then pattern secured to FB, then router/needle saw on top. Using either the cutting needle itself or inflation type needle to follow the pattern. I'm guessing the needle alone will not work as a guide, may be too flexible. If it did work alone, the length of stroke would be important, it could not be too long. I'm guessing it would not work at all on A & B cuts. It would only be practical on outside cuts & possibly to cut a hole for a servo or a spar tab. You would still need to do score cuts by hand, with a knife.
 
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Merv

Well-known member
#35
What Jhitesma and Merv are talking about made me think about setting one up like a bandsaw.
I use a band saw for my planes now, it works great. You need to forget about tabs and folding a plane like FT does. I cut sides, tops & bottoms, all separately. Then assemble the old school way, like we did for a balsa plane. What makes this system work, you can cut many parts at one time. The most I have done is 8 layers of FB in 1 cut. It did not tax my saw in any way, I've just never needed more than 8 of 1 part.
 

jhitesma

Some guy in the desert
Mentor
#36
Yeah, that's why I'm talking about adding a foot. It would allow for precise depth control in a handheld setup. The foot would ride on the material being cut - but the depth the needle protrudes below the foot could be varied.

On my CNC I just use the Z axis to control this allowing me to do score cuts and even "marking cuts" which basically just dent the top layer of paper but don't even cut through it (though I usually do let it just slightly cut the top layer of paper to make the marks more visible.)

You don't really want to adjust the amount the needle protrudes from the guide at full extension in my experience since that can affect performance quite a bit. I like mine setup so the needle retracts fully into the guide at the top of the stroke and then let it extend about 6-7mm past the end when at full extension. That gives me enough depth to fully cut FB but still keeps the needle short enough that it doesn't deflect much so things stay accurate. If you let the needle extend too far then it can deflect while cutting and loose accuracy. If you don't let it retract far enough then heat can be an issue and you can get fluf from the cut building up on the needle.

So instead I picture it where there is a foot which is adjustable so you can control how deep the needle cuts much like the z on my cnc does. But the actual needle travel itself doesn't change.
 

Merv

Well-known member
#37
Yeah, that's why I'm talking about adding a foot. It would allow for precise depth control in a handheld setup.
Instead of a foot, I was thinking having something that covered the whole base. If the base turned out to be 6" x 6", my "depth control" would also be 6x6. I would have several of these with varying thickness to change the depth of cut as needed. When I wanted a through cut, just take them off. When I needed a shallow cut, add the thick needed.
 

Merv

Well-known member
#38
I like mine setup so the needle retracts fully into the guide at the top of the stroke and then let it extend about 6-7mm past the end when at full extension.
So is the total stroke of the needle 6-7mm? Or is the stroke longer to allow the needle to retract more? I'm thinking why make the stroke any longer than necessary, longer stroke = more flexing & more heat.
 

jhitesma

Some guy in the desert
Mentor
#39
The total stroke on mine is about 8-10mm (just guessing since it's not in front of me to measure) but the usable stroke is the 6-7mm that extend out at full extension. I wanted a bit more than the nominal 5mm thickness of DTFB since I've seen DTFB vary by +/-1mm (or more!) and I wanted to account for possible sag in the gantry of my MPCNC due to it's size. It's also nice to have the needle a bit longer than needed initially so you can sharpen it a few times without fully replacing it since you'll lose a bit of length each time you sharpen it.