Guides / Process
Floor Type or Table Type: Which Boring Mill Your Part Needs
September 9, 2026
Both machines have a horizontal spindle and both bore large housings. The difference is what moves, and it changes almost everything about how your part gets machined.
The mechanical difference
Table type. The part sits on a rotary table. The column and the spindle travel in X, Y and Z, and the table rotates the part to present the next face. The table’s rotation is a calibrated machine axis.
Floor type. The part sits on a fixed floor plate, usually at floor level and often too heavy to lift. The column travels on long rails and drives up to the part. There is no rotary table under the part, so to reach another face the machine moves around it, or the part is turned over by crane.
Everything below follows from that.
What the table type gives you
Position between faces without re-indicating. This is the big one. Bore one face, index the table 180 degrees, bore the opposite face. The relationship between the two bores comes from the rotary axis, which is a known and calibrated thing. That is how a gearbox housing gets coaxial bores on opposite faces without a second setup.
Faster setups. One indication at the start, then the table does the rest.
Better repeatability on a batch. The table position is a number, so the second and tenth pieces go in the same way.
The limit: table load and table size. Past that rating the part cannot go on the table whatever the drawing says. See table load and crane capacity.
What the floor type gives you
No weight limit from a table. The part sits on a floor plate or on the shop floor itself. Capacity is limited by floor loading and by the crane that put it there, not by a rotary table rating.
Very long parts machined in one position. Column rails can run tens of metres. A long welded frame can be machined along its whole length without being moved.
Access to big awkward shapes. Nothing is underneath the part except the plate it stands on, so tooling can come at it from further round.
The trade: every face needs the machine to re-establish its relationship to the part. That takes time, and the accuracy between faces depends on the alignment procedure and the operator rather than on a calibrated rotary axis. It is entirely achievable to high accuracy, it just costs more hours and more skill.
Side by side
| Table type | Floor type | |
|---|---|---|
| Part weight limit | Table rating | Floor loading and crane |
| Accuracy between faces | From the rotary axis, high | From re-alignment, operator dependent |
| Setup time per face | Low after the first | Higher, alignment each time |
| Very long parts | Limited by table length | Excellent, rails can be very long |
| Batch repeatability | Strong | Weaker |
| Typical parts | Gearbox housings, pump bodies, bearing blocks | Large frames, press structures, machine beds, in-situ work |
Which one your part wants
Work through this in order.
- Is the part over the table rating of any shop on your list? If yes, you are on a floor type and the rest of the questions do not apply.
- Do features on different faces have to line up tightly? If yes and the part fits a table, a table type will be cheaper and more certain.
- Is the part very long relative to its width? Floor type rails handle that better than any table.
- Is it a batch? A table type will repeat more consistently across pieces.
- Does it need machining in its final assembled position? Then you are looking at a floor type or at on-site machining.
What this means for your RFQ
You do not need to specify the machine type. In fact it is better not to, because a shop with both will pick the cheaper route for the same result.
What you should do is give the shop the information that lets it choose: the envelope, the finished weight, and which relationships between faces actually matter. That last one is what tips a part towards a table type, and if you do not say it, the shop cannot use it.
Read tolerance across a large part for how to express that on the drawing.
What to do next
When a quote comes back, ask which machine it is planned on and how many times the part is turned over. If a floor type quote assumes three re-alignments and a table type quote assumes one index, you have found the reason the prices differ.
Related: horizontal boring mill or gantry mill.
Frequently asked questions
Which type is more accurate?
A table type, for relationships between faces, because the rotary table indexes the part on a calibrated axis. A floor type has to re-align to the part for each face, which is slower and depends more on the operator.
Why use a floor type at all?
Weight and size. A floor type has no table limit, so it takes parts that no rotary table could carry. It also lets a very long part be machined in position without lifting it back onto a table.
Can one machine be both?
Effectively yes. Many floor type mills have a separate rotary table in the working area, so smaller parts get the table type advantages and larger ones sit on the floor plate. Ask what the shop actually has.
Need a quote for a part like this?
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