Width of gap X axis makerslides

I am going to use aluminum .1875 thick and 3.6" wide with a T piece attached to the bottom of the plate. It will just clear the carrage above the rails and just clear the carrage below the rails.

Dave

The MS will take up to 6mm diameter bolts. You can get more T slot nuts from inventables and 5mm button head cap screws to go with them.

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Angus
No the hole in the end of the MS is for 5mm threads only. I was referring to the width of the T slots in the MS they are 6mm wide.

Dave

Metal can extend all the way down to the bottom of the X-carriage, but the screws holding the upper X-carriage rollers stick out over the gap. A quick eyeball measurement across them gave me about 2.9" height. I could be off by 1/8", and you can make the measurement while youā€™re assembling it, but trust me when I say that it sucks to have to cut off a 3ā€™ length of 3/16" steel because you bought it too tallā€¦ :smile:

@MikePlummer, I donā€™t think there would be a significant difference if you went with aluminum unless youā€™re going for levels of accuracy that are beyond the machineā€™s capability. I havenā€™t run the model (and donā€™t plan to), but my engineering gut tells me that a 2-1/2" tall piece of aluminum will absorb any siginificant flex caused by the weight of a decent router. I chose to go with steel just to get extreme accuracy, and because there wasnā€™t any decent pieces of 3/16" aluminum available.

Speaking of decent, make sure your bar stock is straight (especially with steel). I bought the next-to-last piece in the stack because the rest were slightly bowed or twisted. I would prefer not to fight with the steel, itā€™s much better to just slip it in and clamp it up.

My steel spline was too tall when I bought it. After trying to trim it I quickly found that it was not going well. I drove to a local machine shop that had a giant metal shear and they guy there put it in there and 1 second later it was the exact size I wanted. Nice and straight cut and didnā€™t cost a Penney!

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Iā€™ve saved up almost enough for the 1000 kit with the DW611. Since that addresses the spindle upgrade, Iā€™m watching the x and y rail and z carriage upgrades. (I wonder how long before Inventables starts selling a ā€œstiff kitā€?)

The 3/16" plate for the x rails seems to be well received for eliminating sag in the z axis. Does the plate also help with flex in the y direction? Iā€™m wondering if an angle on the bottom edge (or using tee bar) might be helpful, or if it would simply be overkill.

Iā€™m curious to know if anyone has compared steel vs aluminum to see if thereā€™s a meaningful difference in rigidity. Primarily for weight. While the steppers can certainly move the additional mass of steel, any weight reduction would help prolong their life and would also help reduce momentum. Although, the additional weight would provide some damping benefits. Anyway, if the steel doesnā€™t help with y axis flex, then you might reduce the weight by drilling out the plate. It shouldnā€™t affect the z axis support much if any. Or use a thinner stock and shims.

The y rail support seems like a good idea as well. The y rail seems to carry about as much weight as the x rail, but with a single makerslide instead of two. If flex in the z axis is a problem for the x rail, then itā€™s certainly a problem in the y rail. Anchoring to the waste board with an L bracket would provide both z axis support and help eliminate x axis flex. Has anyone evaluated the x axis flex of the y rail while in operation? If x axis flex is not a problem, then why not simply bolt on a piece of flat steel to the inside of the y rails to provide z axis support?

Lastly, instead of drilling and bolting in a plate, I wonder if a steel tee bar could be inserted into the bottom channel of the makerslide. If one could find the right size tee (or have something cut down) then it would be a slip in modification and would require no other fabrication or physical modification. And it would work for both the x and y rails. (Take note, Inventables!)

Anyway, my thoughts, as I save up a little more before I dive in.

I did theoretical calculations and computer simulations yesterday to compare different heights, and also to compare steel to aluminum.

A 3.5 in. tall steel bar was 14% stiffer, compared with a 1.5 in. tall steel bar. However, the weight increases by 57% for the larger bar. For a steel and aluminum bar of the same dimensions, the steel bar was found to be 68% stiffer. The weight decrease is 63% compared with steel.

I originally wanted to go with a smaller piece of aluminum because of the light weight and easy machinability, but decided to delve a little deeper to see how much of a difference steel would make. I ended up purchasing a 3/16" x 2.5" piece of steel because the overall weight (less than 3 lbs) isnā€™t enough for me to worry about the stepper motors moving smoothly, and the added stiffness is exactly what I am looking for in this upgrade.

The reason the steel plate is bolted and not attached using another method is because this prevents slipping between the makerslides and the steel plate. If the pieces are allowed to slip, the forces produced from the spindle will transfer less easily between the pieces of makerslide, allowing for more twisting.

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Read further up thread and all of this is covered. These two simple mods and your Dewalt will get you going. This forum will likely answer all of your initial questions. During assembly, search the forum at each step and you will find valuable tips. Here is an example of the Y mod and yes, most people do both:

Uploading IMAG0684.jpgā€¦

Iā€™m measuring the gap between the x axis makerslides at 4.82mm which seems a bit wider than discussed here.
Iā€™ve measured the v-wheel washers at 0.7mm which is less than the spec listed for the 25287-08 which is .9 - 1.01mm. This may account for the discrepancy.
Iā€™ll have o check this again tomorrow, (well later today) after some sleep.

Geoff

Would this mod allow for a 1800mm gantry? Or would that require other means of reinforcement?

My gut feeling tells me that while it would work for an 1800mm gantry, the weight cause further issues (need bigger steppers, more bracing on Y axes, etc.). If you were to remove 1/3 of the material by drilling holes or making it somewhat like a lattice, it should be effectively the same but lighter. You could also move up to lighter, stronger materials (like titanium), but that would increase the price.

Some people have used bolts and washers vertically to lock the makerslides together, but my instinct tells me that the best stiffness on a long gantry would come from the friction of a plate between the slides, especially if itā€™s got a heavy spindle.

A lot of it would also depend on what type of spindle youā€™re going to be using. Every additional ounce on an extended gantry is going to increase the need for stiffening, so using a heavy router with a heavy dust shoe and the weight of a vacuum hose is going to require more stiffening for correction.

Even the material can make a difference. Milling a hard material like a metal requires a lot of stiffness, because it doesnā€™t take much sag to cause the bit to go too deep and break.

It can be done, and Iā€™m sure others on here have some great ideas on it. What material are you planning to mill, and what spindle are you thinking about?

When I added the 3/16" steel bar to my 1000mm X-carve to stiffen the axis, I didnā€™t even have to increase the voltage to my steppers. The extra weight had no adverse effect on my machine. With an 1800mm gantry the weight would be more, but Iā€™m not sure if it would be enough to require anything other then a bump in the voltage to the y-axis pots. Just my thoughts.