Sliding Legolini - FAQ

General

1) Is this for sale? Can i buy one from you?
No. You can print on a 3D printer. Maybe it will be on sale in the future.

2) I don't have a 3D printer, can you print one for me?
This is not possible because 3D printing takes a long time. Ask your friends.

3) I don't have a 3D printer, would it be possible to get blueprints so it could be made out of wood?
Unfortunately, these are two different materials and technologies. A new project must be made.

4) Is this a crossbow?
No. It does not fit the definition of a crossbow. It's a bow because it can't be locked in cocked condition. Technically, it's basically a slingbow.

5) Are you planning on doing a crossbow as well?
The crossbow is regulated by law in Poland, so I can't do it.

6) I wondered about changing the grip or dart exit port design to reduce the risk of part of the users hand covering the exit port when it's fired?
Covering the arrow guide with your hand is practically impossible, unless intentionally. With normal bow holding, the distance of the index finger to the axis of the arrow is at least about 30 mm.

7) Can you improve the power range?
No. It's more a toy than a weapon.

8) What pound is the bow rated at?
On black rubber around 22 lbs, on silver around 30 lbs. Check test results.

9) FPS?
Up to about 150 fps with silver rubber 6.0 cm on each side and cheap plastic bolts as ammo. Check test results.

10) Shot energy?
Up to about 7 Joules with silver rubber 6.0 cm on each side and cheap bolts with aluminum shaft as ammo. Check test results.

11) Can you share STEP files?
I do not share STEP files.

3D printing

1) It was all made of PLA?
Yes, but you can use also PETG or ASA.

2) Do you print support structure?
I printed without supports. Note the direction of bridging as shown in the PDF manual.

3) The sanding after printing took me 5 hours. I had problems fitting the parts together.
It shouldn't take more than 15-20 minutes. You should calibrate your 3D printer.

4) How should i print the "magazine_part3"? You wrote, that i need a printer with a dimension of 200x200 mm. But the "magazine_part3" is 238 mm.
Turn it 45 degrees.

5) Vertical supports for "magazine_part1" - they don't seem to appear after slicing in Cura and when I attempt to print the vertical pieces don't print either.
Select the "Print Thin Walls" option in the "Shell" tab.

Hardware parts

1) Could you confirm the inner and outer diameter about TheraBand tubes. I'd like to buy it by Aliexpress but it's plenty of black tubes.
TheraBand tube black - ID/OD about 4,5/9 mm. TheraBand tube silver - ID/OD about 5/10 mm.

2) In your instruction you say black but in Jörg Spraves video he is using silver rubber. Is there a big difference and is silver to prefer? Or are they much harder to use?
This is an individual matter. Black rubber is more universal for everyone. There is much more power on silver, but you also need more strength to stretch and hold it.

3) How do i get the the knots into the rubber?
Use a screwdriver for example, but be careful not to cut the rubber with it.

4) What springs should I use? What size?
I recommend 8x20x0.8mm springs, but all springs 7-8 mm in external diameter, 19-22 mm in length and 0.7-0.9 mm wire diameter should work. You can also buy longer springs and cut them to the right length.

5) Can I use bed or extruder springs from a 3D printer?
These springs have a wire diameter of about 1.2 mm and are too strong. Legolini will not work properly.

Arrows / bolts

1) Where did you get the bolts?
On Aliexpress and in store in Poland. Check some links here.

2) What diameter should the arrows be? What length?
Probably all pistol crossbows bolts described as 6.5 inches are really 6.25 inches (160-161mm) and should fit in the magazine. They usually have a diameter of 6.2 mm or 6.35 mm. The magazine is for arrows with a maximum length of 161 mm + 2 mm clearance. If you have longer bolts, they will not fit in the magazine.

3) Is it possible to 3d-print some arrows too?
One reason it makes sense is to try out the Legolini before you are able to purchase bolts. Factory bolts are well made, cheap and equipped with a steel tip, thanks to which the shots are more accurately fired and have greater firepower.

Something is not working

1) The string wears out pretty fast, shrink tubing doesn't help much.
You can apply a professional solution to serve string, for example.

2) When I push the rear forward, the release needs to be slightly cocked in order to catch the rope. I could only find a bed leveling spring for the springs.
The springs of the bed or extruder have a wire diameter of about 1.2 mm and are too strong. Legolini will not work properly.

3) I'm having a problem where the arrows get pushed into the plastic of the magazine and get stuck.
Probably your steel spring is little too weak. Try to put something flat (plastic, cardboard) 1-3mm thick under it. Maybe you need to take a file and file a bit with "spring_body" under the "magazine_spring" lever, so that the lever reaches the bottom of the magazine without any problems.

4) Only real issue that I’ve had so far is breaking zip ties while shooting. I’ve been trying different sizes and combinations to minimize this. Any ideas?
You don't have the middle string too short? Zip ties often break when hitting something hard. Maybe use a thin strong thread or something instead of zip ties.

5) One problem I am having - if I tip it down with an arrow chambered, it slides out. I am thinking that a brush seal might add enough resistance to fight gravity, but give way under the force of the bow string.
The "magazine_spring" lever should keep the arrows in the magazine, regardless of the position of the bow. Maybe you have too short or too weak steel spring. Try to put something flat 2-3 mm (plastic, cardboard) under a steel spring. This will slightly increase its strength, because it will be pre-tensioned.

6) The rubber hits my hand when fired. Not something to hurt yourself badly but something it would hurt if you fire 30 arrows or so.
You probably need to shorten the rubber so that it is more tight at the start. Maybe you have a little too long ropes. You can also hold the bow slightly at an angle and not straight in the line of shot.

Slingbow version

1) I made the Slingbow V2 version of Legolini. The rubber will be destroyed after maybe 20 shots or earlier.
This is the experimental version. You can try using wax or PTFE and grease the slingbow parts. The middle part of string must be much longer than the regular version and you should serve it.

2) When I draw the slingbow it drags the tube a little against the rear of the arms by the string, the friction causes the band to rip slightly.
The middle part of string must be much longer than the regular version. You can try serve string with a thread and use thin string instead of zip ties. You can try using wax or PTFE and grease the slingbow parts. It should help.