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How to Use a Faceplate on a Lathe

Guide · Updated October 28, 2026

A faceplate holds work that will not go in a chuck: castings, flat plates and parts that need a bore at an odd location. The part is clamped to the plate, indicated to the feature you need, and counterweighted so the lathe runs smoothly.

Check bore location

Measure from the datum with gage blocks and an indicator. The free Gage Block Calculator builds the stack.

Step by step

Mount the faceplate: Clean the spindle nose and plate, then mount securely.
Locate the part: Lay out and center punch the feature to be machined.
Clamp: Use step blocks and clamps; parallels behind the part if machining through.
Indicate true: Indicate the punch mark or feature, tapping the part until true.
Counterbalance: Add weights opposite heavy offset parts until the plate stays put at any angle.
Run slow first: Start at the lowest speed and check for vibration.
Machine: Take light cuts and keep hands clear of clamps.

Worked example

A 6 lb casting with its center of mass 2 in off-center makes 6 × 2 = 12 lb·in of imbalance. A 4 lb counterweight placed 3 in from center on the opposite side gives 4 × 3 = 12 lb·in, balancing it. Then a 2.000 in bore at 150 SFM: RPM = 3.82 × 150 ÷ 2.000 = 287 RPM; start lower and work up.

Angle plates on faceplates

For bores perpendicular to a flat face, bolt an angle plate to the faceplate and clamp the part to it. This is heavy and offset, so counterbalance carefully.

Common problems

Vibration means imbalance. Movement means not enough clamping or clamps over thin sections. A chattering bore means too much overhang.

Tips

Indicating: indicate a part in a 4-jaw.
Angle plates: use an angle plate.
Boring: use a boring bar.

Worked example: balancing an offset part

An offset part of about 5 lb with its center of mass 2 in from the axis needs a counterweight about 10 in-lb on the opposite side, e.g. 2.5 lb at 4 in. Start at a low speed and check for vibration before increasing.

Common problems: unbalanced faceplate work chatters; reduce speed and add counterweights.

Fuller worked example: counterweighting an offset part

A 10 lb part whose center of mass sits 0.500 in off the spindle axis creates 10 × 0.500 = 5.0 lb·in of unbalance. A counterweight bolted 4.0 in from center on the opposite side needs 5.0 ÷ 4.0 = 1.25 lb to cancel it.

Test by turning the spindle by hand in neutral: it should stay put in any position. Start at the lowest speed and raise it only if there is no vibration.

FAQ

When do I use a faceplate?

For irregular parts that will not fit a chuck.

Do I need to balance?

Yes for offset parts.

What speed?

Start at the lowest speed.

How do I true the part?

Indicate the feature and tap it into position.

Can I use an angle plate?

Yes, bolted to the faceplate.

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