# Increasing the Altmill 4x4 Z height **URL:** \ **Category:** 🧰 CNC Setup\ **Created:** [May 22, 2026, 12:23am UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444 "2026-05-22T00:23:00Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![keglin](https://forum.sienci.com/user_avatar/forum.sienci.com/keglin/32/11959_2.png) [@keglin](https://forum.sienci.com/u/keglin)\ **Post date:** [May 22, 2026, 12:23am UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/1 "2026-05-22T00:23:01Z")
This is just a thought experiment - I don’t have a need for this per se. The 4x8 Altmill has roughly 3 extra inches of Z clearance compared to the 4x4 version. I’m wondering if it would be possible to CNC new Y-axis gantry plates that have an extra inch or two of clearance to improve the capabilities of my 4x4. Now that I mention it, I wonder if the bolt pattern is the same between the 4x8 and the 4x4. If the 4x4 is sufficiently rigid, could we buy the Y-axis gantry plates for the 4x8 and install them? ---
**Author:** ![Jens](https://forum.sienci.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@Jens](https://forum.sienci.com/u/Jens)\ **Post date:** [May 22, 2026, 12:30am UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/2 "2026-05-22T00:30:13Z")
Raising the height of the cross rail is one thing but wouldn’t you also need to increase the z rail travel range? It would be nice to increase the Z clearance and 3" seems like a nice amount that shouldn’t affect rigidity by a lot. ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [May 22, 2026, 12:40pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/3 "2026-05-22T12:40:55Z")
@keglin One thing to consider in your experiment is that, if you simply raise the Y rails to get more Z clearance, you may well have issues with trying to cut through material. End mills are only so long. I raised the Y rails on my LM Mk1 to get more clearance above the Vortex. The downside is that I now need to add a second spoilboard under “normal” thickness material if I want to cut through it with a 1/8" end mill. I think that’s a reasonable tradeoff, but it can be a bit inconvenient. ---
**Author:** ![keglin](https://forum.sienci.com/user_avatar/forum.sienci.com/keglin/32/11959_2.png) [@keglin](https://forum.sienci.com/u/keglin)\ **Post date:** [May 22, 2026, 3:47pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/4 "2026-05-22T15:47:11Z")
That’s what I’m thinking I’ll do. I’m more often limited by the clearance of the gantry than I am limited by the length of my endmills. But if I’m in a situation where that matters, I’ll just chuck on another spoilboard or two ---
**Author:** ![mjeanson](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/f05b48/32.png) [@mjeanson](https://forum.sienci.com/u/mjeanson)\ **Post date:** [May 29, 2026, 7:46am UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/5 "2026-05-29T07:46:19Z")
When and I think it is out the taller Y plates and the stiffing gusset are out in the CAD files for the 4X8 machine. I would like to do this so I can use my A-axis to its fullest. I was hoping to just buy these parts in the future. Maybe if enough of us bug the guys this will be offered as an upgrade kit in the future. I would prefer to get the nice black look that I currently have! As to needing to change the Z on my MK2 I have more than enough travel on it to handle the added height and my longer 2.2KW spindle helps as well. Note that the MK1s gantries do not have the T nut slot on the underside so the gussets bolts would require that a holes bored and would need to be tapped or so I have been told. If they don’t offer this we can pull the files and mill out our own plates and gussets on our current machines! ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [August 15, 2026, 1:55pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/6 "2026-08-15T13:55:06Z")
I added 1" to the Y Axis Gantry Plates in Fusion and then uploaded that to SCS and if you order 10 of each side its about $300 per plate so $600 per machine. The more qty you order the better the price gets per part. I can drop the file here if anyone wants it. ---
**Author:** ![Altmillal1114](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/f6c823/32.png) [@Altmillal1114](https://forum.sienci.com/u/Altmillal1114)\ **Post date:** [August 15, 2026, 10:05pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/7 "2026-08-15T22:05:27Z")
is it worth it for 1"? ---
**Author:** ![Jens](https://forum.sienci.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@Jens](https://forum.sienci.com/u/Jens)\ **Post date:** [August 16, 2026, 12:22am UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/8 "2026-08-16T00:22:43Z")
Only if you have a LOT of heavy timber to deal with. For one extra inch you could just pull the 3/4" spoil board and replace the 3/4 inch (usually) main board with a 1/2" board. For a one-of, if your project fits in between the mill cross rails, you could probably make some sort of temporary surface below the cross member level. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [August 16, 2026, 1:36pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/9 "2026-08-16T13:36:32Z")
For some it may be, others maybe not. I can add more to it, that was just what I started with. Need 4"s then I can make that adjustment and check the cost if ya want. ---
**Author:** ![Altmillal1114](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/f6c823/32.png) [@Altmillal1114](https://forum.sienci.com/u/Altmillal1114)\ **Post date:** [August 16, 2026, 1:57pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/10 "2026-08-16T13:57:28Z")
What’s the max you can do without effecting kinematics? ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [August 16, 2026, 2:31pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/11 "2026-08-16T14:31:38Z")
Many ways to skin the cat, just depends on your wants and needs. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [August 16, 2026, 2:58pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/12 "2026-08-16T14:58:23Z")
Not gonna lie, had to look that word up and still not entirely sure I understand it 🤣 But if I understand the word like I believe I do, I selected the perfect point in the plate to add the extra that only moves the Z vertically, it does not shift the tram +/- in the Y axis. Is that what you were referring to? ---
**Author:** ![Altmillal1114](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/f6c823/32.png) [@Altmillal1114](https://forum.sienci.com/u/Altmillal1114)\ **Post date:** [August 16, 2026, 3:14pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/13 "2026-08-16T15:14:08Z")
sorry about that. I might have used it wrong. But basically what i was asking is what is the maximum addition you can do without introducing flex, loosing ridgitity and having them to beef up X gantry, use gussets and redesigning the entire altmill lol. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [August 16, 2026, 3:15pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/14 "2026-08-16T15:15:01Z")
No worries, I’m just a shade tree engineer so I have no idea! ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [August 17, 2026, 5:17pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/15 "2026-08-17T17:17:27Z")
I asked support about the 4x8 plates and this was the response. “You can’t use the 4x8 plates on the 4x4, they are completely different as they use a rack and pinion system and the motors are mounted on the plates for the Y axis.” ---
**Author:** ![Altmillal1114](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/f6c823/32.png) [@Altmillal1114](https://forum.sienci.com/u/Altmillal1114)\ **Post date:** [August 18, 2026, 10:04am UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/16 "2026-08-18T10:04:35Z")
thats a good point. I have a feeling they are working on mk3 version that will have more travel to accomodate atc racks and possibly higher Z but its tempting to try out your option as well. ---
**Author:** ![Imisky](https://forum.sienci.com/letter_avatar_proxy/v4/letter/i/6bbea6/32.png) [@Imisky](https://forum.sienci.com/u/Imisky)\ **Post date:** [August 19, 2026, 8:46pm UTC](https://forum.sienci.com/t/increasing-the-altmill-4x4-z-height/26444/17 "2026-08-19T20:46:26Z")
I have toyed with the idea of adding 1 more inch to the Y plates just so I don’t have to keep retramming my spindle after I take on and off the vortex. If only I had a 2nd machine to toy with.