Split a part to fit your printer

Your lamp arm is 400 mm long. Your printer's bed is 220 mm. You have three options: buy a bigger printer, shrink the design, or split it into pieces and join them. Solid Vibes makes the last one easy.

1. Know your bed

Choose your printer in your profile, or pick a preset in the Make tab. Presets include:

If your printer is not listed, tell the agent its bed size in millimetres.

2. Let the check find the problem

Open Make and run the 3D Print (FDM) check. If the part is bigger than your bed, you get a bed fit issue, and an auto Split suggestion that proposes where to cut. You can accept it as it stands, or ask for something different.

You can also start by asking:

This arm is too long for my Ender 3. Split it into the fewest pieces that fit the bed, with a dovetail joint at each cut.

3. Choose where the seam goes

The best cut is the one you will not notice or worry about. Think about:

• Low stress. Cut where the part carries little load. A joint at a bend or a thin neck is a weak spot.
• Flat cut faces. Flat faces glue best and print flat on the bed.
• Hidden seams. Cut where a seam will be covered, on the underside or at a natural edge such as a change of shape.
• Away from holes and details. A cut through a screw hole or a mechanism is a headache.
• Balanced pieces. Pieces of similar size print in similar times, and make assembly easier.

4. Pick a joint

A bare butt joint is weak and hard to align. Add a joint feature:

The split makes two Pieces and joins them with a Connection, Glued if you plan to bond them, Press-fit if the joint holds by interference, or Bolted with screws. The pieces appear separately on your Make list.

Split the arm at 190 mm with two 3 mm pins and matching holes. Glued connection. Give the pin holes 0.2 mm of clearance per side.

5. Check the numbers

• Each piece fits the bed (check the bounding box in the Make step).
• Pin or dovetail clearances are right for glue: 0.1 to 0.2 mm per side for liquid adhesive, or a snugger fit if you want the joint to hold without glue.
• No tiny features are left at the cut. A sliver of material is easy to break.

If you will bolt the halves, add inserts or bosses near the cut:

Add two M3 heat-set bosses on each half near the cut, 8 mm from the edge, so I can screw the halves together as well as gluing them.

6. Print and assemble

1. Print each half in its recommended orientation. Print a short test of the joint first.
2. Dry-fit the halves. If tight, sand lightly or raise the clearance parameter and reprint.
3. Glue. Cyanoacrylate (super glue) is quick; epoxy is stronger and gap-filling. Clamp or tape it while it cures.
4. Sand or fill the seam if you want it invisible.

Joining them back

If you change your mind, say "make these one piece" and the agent merges the pieces into one again. This is useful if you later buy a bigger printer.

Strength and honesty

A glued joint is weaker than solid plastic, even with pins. Do not expect a split arm to carry the same load as a one-piece arm. If the part is load-bearing:

• Add a dovetail or a bolted joint.
• Cut where stresses are low.
• Print in a strong material (PETG, nylon).
• Overbuild it and test.

Try it

On the Desk lamp arm template:

The arm needs to print on a Prusa MK4. Split it into the fewest pieces that fit, cut each piece flat so it prints without supports, join them with a dovetail, and show me where the seams are. Keep the hinge ends intact.