Screw PH-Cross Slot M4x35: When to Use This Size in eitech Builds

Quick answer

Use an M4x35 PH-cross slot screw when you need to clamp a stack of eitech parts that measures close to 35 mm and the joint will be tightened from one side with a Phillips driver. If the stack is thinner, step down to a shorter M4 screw; if the screw bottoms out before it grips, the stack is too thin for this length.

An M4x35 screw is a long M4 screw, and in eitech builds that length is usually chosen for one reason: you are joining several layers of metal parts and need the thread to reach through all of them before it bites. Getting the length right matters because eitech parts are thin, and a screw that is too long can bottom out, crush a spacer, or leave a sharp point exposed on the far side of the model.

This guide walks through the practical checks for choosing an M4x35 PH-cross slot screw, from measuring the stack to testing the first turn. It also covers when a shorter screw is the better call, and how to handle replacements when a screw goes missing from a kit.

What M4x35 actually means in an eitech build

M4x35 is a size callout: M4 is the thread diameter, and 35 is the nominal length in millimetres. In a PH-cross slot screw, the head has a Phillips-style cross recess, so you drive it with a cross-head screwdriver rather than a flat blade. That combination is common in metal construction sets because the cross recess gives you more torque before the driver slips out of the slot.

The length is measured from under the head to the tip on most screws of this type, so the 35 mm figure tells you how much screw shank is available to pass through your parts. That is the number you compare against your stack of eitech plates, strips, and brackets. If the stack is much less than 35 mm, the screw will protrude or bottom out; if it is close to 35 mm, the screw is doing its job.

• Check the screw head style before you start: PH-cross needs a cross-head driver, not a flat blade.
• Measure the stack, not the individual part, when deciding on length.

Measure the stack before you pick the screw

The single most useful step is to hold the parts together in the order they will be assembled and measure the total thickness at the joint. Include every plate, strip, bracket, and any washer or spacer that sits under the head. That total is the stack height, and it is what the 35 mm length has to cover.

If the stack measures around 30 to 35 mm, an M4x35 screw is a sensible starting point because it will pass through the full stack and still have thread left to engage. If the stack measures noticeably less, say 20 mm, a 35 mm screw will stick out well past the last part. That is not automatically wrong, but it changes how the model looks and feels, and it can catch on other moving parts.

• Stack height is the deciding number, not the size of any single part.
• If you cannot measure, compare the screw against the assembled joint before tightening.

When a shorter screw is the better choice

Shorter M4 screws are usually the better choice when the joint is only two or three thin parts deep. A long screw in a shallow joint has more exposed shank, which can interfere with moving assemblies such as a crane arm or a tipper mechanism. It also puts more leverage on the parts if the model is handled roughly, which can bend thin metal.

A good rule is to use the shortest screw that still passes fully through the stack and engages the thread. If an M4x35 screw bottoms out before it grips, the joint is too thin for that length and you should step down. If a shorter screw will not reach through the stack, step up. The screw should feel like it is pulling the parts together, not forcing them apart.

• Use the shortest screw that still passes through the whole stack.
• If the screw bottoms out before it grips, the joint is too thin for that length.

Driving a PH-cross slot screw without stripping it

Cross-slot screws strip when the driver is the wrong size or when you push too hard at an angle. Use a cross-head screwdriver that fills the recess, keep it straight, and apply firm downward pressure while turning slowly. Let the thread do the work. If the screw stops turning before the parts are tight, stop and check whether it has bottomed out or cross-threaded.

Metal construction sets reward a light touch. Start the screw by hand for the first turn or two so you can feel whether it is seated correctly, then finish with the driver. If you feel resistance that increases suddenly, back the screw out and inspect the hole and the screw tip before continuing.

• Match the driver to the cross recess; a loose driver is the main cause of stripped heads.
• Start by hand for the first turns to feel whether the screw is seated straight.

Replacing a missing M4x35 screw

If you lose an M4x35 screw from a kit, the replacement needs to match both the thread and the length. A screw of the same diameter but a different length may not reach through the stack, or it may protrude where the original did not. Check the kit documentation or the remaining screws in the same bag to confirm the size before ordering.

For small parts like screws, rims, and cord wheels, eitech sells individual components through the Manufaktur range, which is useful when you only need one or two pieces rather than a full set. That means you can replace a single missing screw without buying a whole new kit, provided you can identify the size correctly.

• Match both thread diameter and length when replacing a screw.
• Keep a few spare screws of common sizes on hand so a missing one does not stop a build.

Step-by-step: choosing and fitting an M4x35 screw

1. Assemble the joint dry: Hold all the parts that the screw will pass through together in the order they will be fixed, without the screw. Checkpoint: the parts should sit flat against each other with no gaps you cannot close by hand.
2. Measure the total stack height: Measure from the top surface where the screw head will sit to the last part the thread needs to reach. Checkpoint: if the stack is close to 35 mm, an M4x35 screw is a reasonable fit; if it is much less, consider a shorter screw.
3. Test the screw by hand: Start the screw into the first thread by hand and turn it two or three times. Checkpoint: if it binds immediately, stop and check the thread and alignment before using a driver.
4. Tighten with the correct cross-head driver: Use a cross-head screwdriver that fills the recess, keep it straight, and tighten until the parts are snug. Mistake to avoid: over-tightening, which can strip the screw head or crush thin metal parts.
5. Check the far side of the joint: Look at where the screw exits the last part to see how much shank is exposed. Checkpoint: if the screw protrudes a long way or blocks a moving part, switch to a shorter screw.
6. Record the size for next time: Note the screw size and where it was used in your kit documentation or a small parts list. Next step: keep a few spare M4 screws of different lengths so a missing screw does not halt a build.

eitech parts that pair with M4 screws

• Cord wheel Ø 14 mm: The eitech Cord wheel Ø 14 mm is a small cord wheel component offered under SKU 01311 in the Standard variant, part of the eitech Manufaktur range, with a 14 mm diameter. Small wheels like this are often mounted with M4 screws, so checking the stack height at the wheel mount helps you choose the right screw length.
• Rim Ø 25/4 mm, with profile hole: The eitech Rim Ø 25/4 mm is a Manufaktur component with a profile hole, offered under SKU 01301P as the Standard option. Rims and wheels add thickness to a joint, so include them in your stack measurement before deciding whether an M4x35 screw will fit.
• Rack profile B slider, white: The eitech Rack Profile B Slider in white is a component from the eitech Manufaktur line, offered in the Standard variant under SKU 01870.01_WEIß. Sliders and rack parts are often fastened with screws, and their thickness affects whether a long screw like the M4x35 is appropriate for the joint.

An M4x35 PH-cross slot screw is the right choice when your eitech joint stack is close to 35 mm and you need a cross-head drive. Measure the stack first, use the shortest screw that reaches through it, and drive it straight with a matching cross-head driver. That habit keeps threads intact and models solid.