Hello everyone,

I am a furniture designer/maker who makes sculptural pieces of furniture out of solid wood. I have no experience with CNC, but I am sure that I will be able to incorporate one into my one-of-a-kind work flow. I am very excited about the whole process!

I have been developing a design for a machine that synthesizes my needs with what I have learned from other posts. I know enough now to know that I know very little. Any comments or guidance would be greatly appreciated.

The overview of the machine is: welded steel base, 8020 extrusion, plate aluminum cars, Hiwin linear rail, R&P, 4KW Chinese spindle with VFD and Nema 34 steppers…(all subject to your review). I am approaching the build in a few stages that will be spread out over the coming year.

Clear space in my studio and evaluate size
Weld the base
x & y rails and cars
z car
steppers & spindle
Electronics
Learn how to use it!

I am at the point where the various components are starting to work as a system in my CAD drawing. Thats the good part…the bad part is I am now seeing flaws in my plan and other areas of my inexperience are totally exposed! I have some specific questions in regard to sizing Hiwin blocks and in regard to setting up the Z axis. I will do my best to walk you through my design which will explain the thought behind some of my decisions. I am open to any and all suggestions that help me reach my goal of a capable CNC router for hardwoods. If the machine is rigid enough I could easily find some aluminum projects for the machine.

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Base: The size of the base is the big issue for me. My studio is a fixed size with no hope of expansion. It would be ideal to have a machine that could accommodate sheet goods, but it is far from mandatory. In reality 30” of cutting width would be fabulous for my workflow. The long axis is more important to me and cutting 8 plus feet will be very useful. I mention the size because the design of the machine tries to maximize the cutting with of a narrow machine. I should point out that my machine will keep the top of the 80/20 rails below 34”. I realize that this is quite short short, but it affords me the freedom of allowing many of my other machines to pass material over the cnc.

The base will be welded out of 14g steel with levelers. I can’t expect the base to be either flat or square enough for my taste. I plan on using the aluminum plates as a transition to the 80/20 so that I can either flatten or shim with the help of my 6’ Starrett straight edge and machinists level.

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Spoil Board: I plan on having three layers of 3/4” material. The cut out in the front of the machine is for vertical work. I plan on hinging the plate so that it can angle to 45°. This will mimic some of the functionality of my multirouter but add CNC awesomeness! I should probably remove the bar in front of that part of the table but I am protecting my dream of supporting a full 4 x 8 sheet.

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Y-Axis:

The rails will be made from 2040 series 10 80/20 extrusion attached from below and attached to the short sections of angle iron (to help reduce the tendency to rack). The Y cars are made of 3/4” aluminum with some of the vertical components made from 1/2”. I have designed the cars to allow for maximum movement in the x direction, a concession to the limited space in my shop. I have read enough about the Hiwin rails to know that I will be limited in terms of what legacy blocks I can actually find. I am curious if these blocks are adequate? LGW20HBZ1H blocks and rail. If I cant find them can I use the standard precision? What about the preload? For some reason I decided that Z1 appropriate?

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X-Axis
3060 series 15 extrusion is at the core of the x axis. The same hiwin block and rail as the y axis are mounted on the top and bottom of the extrusion. Same questions about preload, precision and size?The spacing of the blocks also tries to maximize the reach of the router in the x direction.

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Z-Axis
This is where my plan kind of unravels. All of my efforts to maximize the x axis movement crash up against the reality of clearing the spindle and my lack of experience. I have many questions: What is the relationship of the bottom of the spindle to the bottom of the Z plate? My design has the blocks permanently mounted and the stepper, ballscrew rails and plate moving. How high up should the spindle be able to go? I would like to get the bottom of the collet in line with the bottom of the x car. The answer to the first question effects how high I need to move the bottom hiwin block. If I try to achieve this I end up with the spindle hanging way below the bottom Hiwin block. Am I going for too much movement? Am I going about this in the wrong way? Perhaps I should explore pre-made Z options?

Here are the images that illustrate some of my many Z axis questions:


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If I line up the mounting holes on the spindle with the bottom of the z plate I will have to move the bottom hiwin block up much higher.
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moving the blocks up will result in quite the overhang of the spindle. I have been looking at other machines and it seems that this sort of overhand is not unheard of.
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Many thanks for having a look at my plan.