On December 3, 2025, Sienci published the full details of the AltMill automatic tool changer (ATC), with kit prices that replace the range it floated in October. A 6-tool kit is $2,890 USD, or $4,040 CAD. A 12-tool kit is $3,340 USD, or $4,670 CAD. The spindle by itself is $2,590 USD, or $3,620 CAD.
Add-ons are priced separately: an extra rack is $245 USD, holders are $28 each, and the air filter-regulator is $80. Canadian prices for those parts are $340, $38, and $120. TMWB has not tested the changer, so everything here is Sienci's information from the December 3 post.
What is an automatic tool changer?
An ATC stores several cutters and swaps them under program control. On a wood router that usually means a roughing bit, a finishing bit, and a V bit for lettering, without you standing there with a wrench. Sienci's version is built for the AltMill MK1 and MK2 in the 2×4, 4×4, and 4×8 sizes. It isn't compatible with the LongMill. That sentence is doing a lot of work, because a lot of Sienci owners have LongMills and will ask about it anyway.
What's in the spindle and holder system?
The spindle side uses ISO20 holders with ER20 collets, a pneumatic drawbar, and an onboard controller board. ISO20 is a standard tool-taper size, which is the cone on the holder that locks into the spindle. ER20 is the collet series, a split sleeve that handles the shank diameters most wood routers use, up to about 1/2 inch. The drawbar is the air-powered claw that pulls the holder into the spindle.
The kit also includes a temperature-controlled fan that Sienci describes as quiet, an air blast to clear chips at each change, an integrated tool-length sensor, and the Clear Cut dust shoe as standard. There's an LED and a button for a manual tool change when you want to do one yourself. The rack comes off with two screws.
How does the air supply work?
You need a compressor that can supply at least 3 CFM (cubic feet per minute, a measure of volume) at 90 psi (pounds per square inch, a measure of pressure), and 100 psi minimum. Air gets used at the tool change and then rests during the cut, which is why Sienci says a normal consumer compressor is enough. A compressor that reaches 100 psi but refills slowly could still sag if tool changes come in a cluster.
The air blast clears chips so the next holder can seat cleanly in the same cone. Budget for the $80 filter-regulator ($120 CAD) and for a compressor. The kit includes neither the compressor nor the filter.
How does the controller keep track of tools?
gSender, Sienci's sender software, knows about the changer. The controller can store up to 32 tool-length offsets even though you only have 6 or 12 physical pockets. An offset is the stored length of a tool, so tool 4 doesn't cut at tool 1's height.
A dirty holder can change the number the program believes, and the post doesn't say how forgiving the sensor is. A broken bit in pocket 3 will happily start the next operation, so "unattended" still means trusting the dust shoe, the air, and the tool-length sensor. Sienci doesn't claim this is a lights-out cell.
What are the electrical requirements?
Power is 220 V at 10 amps or more. Ten amps at 220 volts is 2,200 watts, the same 2.2 kW class as the air-cooled spindle in the October teaser. A step-up transformer can raise a 110 V shop, and Sienci notes the breaker still limits the current. This is the point where a garage circuit becomes the project.
Drawings for people who want to hang the spindle on some other router are promised later. There's no third-party support on December 3.
How do the prices add up?
The 6-tool kit is $300 USD above the spindle-only price ($2,890 versus $2,590), or $420 CAD ($4,040 versus $3,620). Stepping from that kit to the 12-tool kit costs another $450 USD, or $630 CAD, and the larger magazine is already in the $3,340 price. Buying holders one at a time is the slower route. The filter-regulator is extra whichever way you go.
Sienci's October 22 teaser had floated about $2,500 to $3,000. The 6-tool kit lands inside that range, and the 12-tool kit doesn't, so if you budgeted from the teaser, read the kit list again before you check out.
On a 4×8 frame at $7,490 without a spindle, the published prices come to $10,380 with the 6-tool kit and $10,830 with the 12-tool kit. I added those figures myself, and the filter and the compressor remain outside the sum. Sienci held a Q&A on December 4 with Johann and Kevin.
Who is it for, and what's still unknown?
In December 2025, a tool changer under $3,500 on a router whose 4×8 frame starts at $7,490 is how a small shop gets unattended-looking jobs without buying a machining center. It fits people who already own an AltMill, or are ordering one, and who have 220 V or a plan to get it. LongMill owners are explicitly out.
What's still unknown on December 3 is the ship date for the first kits, how loud the air blast is in a small room, and how forgiving the tool-length sensor is when a holder is dirty. The prices, the air specification, and the LongMill exclusion aren't unknown. They're in the post.
Sources and image credits
- Everything you need to know about the ATC (Sienci Labs)
- Sienci AltMill
- Product images: Sienci Labs ATC announcement post
