Setup Guide

How to Set Up a Shopsabre CNC Machine

This guide covers how to set up Shopsabre CNC machine in the order we use in our own shop: inspect the machine, load and measure tools, set work offsets, verify the program, then take a safe first cut. Written for operators and shop engineers who want a repeatable setup, not a checklist that skips the checks that matter.

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Pre-power checksTool length offsetsWork offsetsFirst-cut proofing

On this page

Key takeaways

Setup is a sequence, not a listMachine inspection, tool offsets, work offsets and dry run all happen before the spindle turns.

Measure every toolTool length and diameter go into the controller from a tool setter, not from the label on the holder.

Zero from one datumPick a corner or a bore, touch off with an edge finder, and keep every offset tied to that point.

Dry run in air firstRun the program 25-50 mm above the stock to catch wrong offsets and rapids before metal moves.

Cut a test passOne shallow pass at reduced feed confirms tool load, coolant and chip clearance before full depth.

Before power-up

What to check before you set up a Shopsabre CNC machine

A Shopsabre router or mill is a gantry-style machine, so the setup starts with the rails, not the controller. Walk the table first. Wipe the linear rails and the rack, then look for dried chips or resin buildup that can make an axis jump during a rapid move. A single chip under a bearing block shows up later as a step in the finish.

Check the spindle and the collet. Spin the spindle by hand with the power off and listen for grit. If the machine has an ATC, pull each holder and look at the taper. Any fretting or blue marks mean heat, and heat means the holder is not seating. Fix that before you set tool offsets, because a loose taper changes length when the spindle warms up.

Confirm air and coolant. Most Shopsabre machines need 6-7 bar of dry air for the counterbalance and the tool-change cylinder. Drain the water trap first. If you run a mist or flood coolant, check the nozzle aim with a manual pulse, not by guessing. A nozzle that hits the cut from behind the tool will not clear chips.

1
Power offDo every mechanical check with the disconnect open and the spindle stopped.
2
Clean railsDry chips and resin are the most common cause of a rough first cut.
3
Air firstDrain the trap and confirm 6-7 bar before any tool change.

Tooling

Loading tools and measuring offsets

Load the holders in the order the program calls them. If the code uses T1 through T6, put those tools in pockets 1 through 6. Do not skip a pocket to save time, because the controller will pull the wrong holder and you will cut with a rougher where a finisher was planned. Write the tool number on the holder with a paint pen so a second operator cannot mix them up.

Measure length and diameter with a tool setter or an offline presetter. Enter both numbers into the offset table. For a 6 mm flat end mill in aluminium, a common starting point is 12,000-16,000 rpm, 1,500-2,500 mm/min feed, and 1-2 mm depth of cut. For a 10 mm tool in mild steel, drop to 3,000-5,000 rpm and 400-800 mm/min. These are starting bands, not fixed values. Listen to the cut and adjust.

Set the tool change height with clearance. The Z should retract at least 25 mm above the tallest fixture before any XY move. On a gantry machine the gantry itself is a moving mass, so a short retract is a crash waiting to happen. Check the height against the longest tool in the carousel, not the tool currently in the spindle.

1
Match pockets to codeT1 in pocket 1 keeps a second operator from loading the wrong tool.
2
Measure, do not trustHolder labels drift after a re-grind. Use the setter every time.
3
Clear the tallest toolSet the retract height against the longest holder, not the current one.

Workholding

Setting the workpiece and work offsets

Decide where the datum lives before you clamp anything. On a flat plate, we use the front-left top corner as X0 Y0 Z0 so the program matches the drawing. On a part with a finished bore, a bore center is a better datum because the corner may have a saw burr. Touch off with an edge finder at 600-800 rpm, or use a 3D taster if the machine has one. Write the numbers down; do not carry them in your head between setups.

Clamp so the part cannot move, but do not bow it. On a vacuum table, check the seal and the vacuum level before you trust it. On a vise or toe clamps, put the clamps where the cutter will not reach them. A common mistake is clamping over a pocket; the tool hits the clamp and the part shifts. Mark the clamp positions on the setup sheet.

For thin plates, add support under the cut. A 3 mm aluminium plate will sing and lift if the area under the cutter is unsupported. Back it with MDF or a fixture plate, and take lighter depths. If the part has holes, use them for dowel pins so the position repeats when you flip the part for the second operation.

1
One datumPick a corner or a bore and tie every offset to it.
2
Clamp clearKeep clamps outside the toolpath and note their positions.
3
Support thin stockBack thin plates to stop chatter and lift.

Step by step

Step by step: how to set up a Shopsabre CNC machine

Follow the order. Skipping a step moves the error to a more expensive place.

1
1. Lock out and inspectOpen the disconnect. Clean rails, rack and table. Check the spindle by hand, the air trap and the coolant nozzles. Fix anything loose before power-up.
2
2. Home the machinePower up and reference all axes. Let the spindle warm up at 2,000-4,000 rpm for 5-10 minutes so thermal growth settles before you measure offsets.
3
3. Load and measure toolsPut holders in the pockets the code calls. Measure length and diameter on the setter and enter both into the offset table. Set the Z retract at least 25 mm above the tallest fixture.
4
4. Mount and indicate the stockClamp the part so it cannot move. Indicate the datum edge or bore within 0.02 mm. Check that no clamp sits in the toolpath.
5
5. Set work offsetsTouch off X, Y and Z at the datum. Enter the values in G54. If you run a second vise or a second part, use G55 and keep the same datum logic.
6
6. Dry run in airRaise Z 25-50 mm above the stock. Run the program with feed override at 100% and watch the distance-to-go. Stop on the first unexpected move.
7
7. Test cut and prove outCut one shallow pass at 50% feed and full rpm. Check chip color, sound and finish. If it is clean, step up to the programmed depth and feed.

Settings

Starting parameters by material and tool

Use these as a first pass, then adjust from the sound and the chip.

Material	Tool	Spindle speed	Feed and depth
Aluminium 6061	6 mm flat end mill	12,000-16,000 rpm	1,500-2,500 mm/min, 1-2 mm DOC
Aluminium 6061	10 mm 3-flute	8,000-12,000 rpm	2,000-3,000 mm/min, 2-3 mm DOC
Mild steel 1018	10 mm carbide	3,000-5,000 rpm	400-800 mm/min, 0.5-1 mm DOC
Stainless 304	8 mm carbide	2,500-4,000 rpm	300-600 mm/min, 0.3-0.6 mm DOC
Plastic POM	6 mm 2-flute	10,000-14,000 rpm	1,500-2,500 mm/min, 2-4 mm DOC
Wood or MDF	6 mm 2-flute	16,000-20,000 rpm	3,000-5,000 mm/min, 3-6 mm DOC

The short version

If you set up a Shopsabre CNC machine in this order, most crashes and scrap parts are caught during the dry run, before the spindle touches metal.

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FAQs

Frequently asked questions

How long does a Shopsabre setup take?

For a repeat job with the fixture already made, a clean setup takes 20-40 minutes: home, measure tools, touch off and dry run.

A new part with a new fixture takes longer, often 1-2 hours, because you are proving the datum and the clamp positions as well as the offsets.

Why does the first part come out undersize?

The most common cause is a tool length offset that was measured cold. The spindle grows 10-30 μm as it warms up, so the tool cuts deeper than the offset says.

Warm up the spindle before you measure, and re-check the first part rather than trusting the offset table.

Should I use G54 or G55 for a second vise?

Use G54 for the first vise and G55 for the second, but keep the same datum logic on both. If the first vise zeros on the front-left corner, the second should too.

Mixing datum logic between offsets is how a part gets cut on the wrong side of the stock.

How high should the Z retract be?

At least 25 mm above the tallest fixture or clamp, and against the longest tool in the carousel, not the tool in the spindle.

On a gantry machine a short retract is a crash risk, because the gantry moves as a large mass and does not stop instantly.

What tolerance can a Shopsabre hold?

A well-maintained machine with a warm spindle and a rigid fixture can hold ±0.02-0.05 mm on a good day.

If the part needs ±0.005 mm, that is a different class of machine and a different setup. Send the drawing and we will tell you which process fits.

Do I need coolant for aluminium on a router?

Not always. A sharp cutter, a good chip load and air blast clear chips well on 6061.

For deep pockets, mist helps. For steel or stainless, use flood or mist, because heat builds fast and the tool will fail.