Cheap DIY Router Challenge !!! - Page 5

# Thread: Cheap DIY Router Challenge !!!

1. ## Re: Cheap DIY Router Challenge !!!

Are you looking at the numbers or the colour and apparent (visual) distortion?
To compare different models / materials you have to look at the numbers. The colour / distortion are not proportional, just to show where things are best / worst.

A uniform force is the wrong model really.

Steel is ~3x stiffer than aluminium (in the same section). Your numbers confirm this.

If you are not used to looking at scientific notation, I suggest changing the settings so you are looking at decimal notation (ie 0.001mm rather than 1e-3)

Alu 0.09671mm max
Steel 0.03435mm max
Flat MDF 2.453mm max (that is 25 times worse than aluminium, and 71 times worse than steel.)
6" MDF 0.02795mm max.

To actually model this, you will need to use a more representative load. It would be best to actually model the MDF torsion box, as it is not the same as a solid. Rib spacing will have an impact. The smaller the area the force is applied to, the more rib spacing will come in to play.

(Apologies if I have misunderstood your post and you already appreciate these things, but they are common mistakes with FEA).

2. ## Re: Cheap DIY Router Challenge !!!

Originally Posted by pippin88
Apologies if I have misunderstood your post and you already appreciate these things, but they are common mistakes with FEA.
I'm not going take offense. Thank you for taking the time.

I supplied max deflection as the main point of comparison for the analysis. The reason for not being too specific is because the model is idealized and not going to be representative of the real world. It should be useful for ballpark comparison of materials under the same idealized conditions (i.e., fixing the material along two edges and then applying a uniform force along the top surface). Hopefully these measurements provide some guidance towards building a structure that meets the overall goals.

Towards that end a major issue is having accurate materials data, an accurate model of the materials, and using the information correctly. Manufactured wood products supply different numbers for perpendicular and parallel properties and that is presenting a major problem for me. I have to change the material depending on the direction of applied force. Makes me feel that there is something I'm missing and the reason why I'm being careful with how I apply load and interpret the results.

A bit confused why you suggest testing a torsion box as that is exactly what the last two models show. And more tellingly, at least to me, is that they show the MDF torsion structure having comparable deflection to steel and aluminum under those idealized conditions. That was a surprise.

Your suggestion of a more representative, smaller area of force is something I intend to pursue as more structure and complexity is added to the model. I assume the holly grail is to build up to a model where force is applied by motors and the spindle ... mostly the spindle. Not there yet.

3. ## Re: Cheap DIY Router Challenge !!!

Wow. Beautiful!

What are you going to use to seal?

This is prolly the simplest and most affordable solution. I can see why so many MDF machines are built.

4. ## Re: Cheap DIY Router Challenge !!!

I seal everything with epoxy prior to painting. It makes painting MDF 100x easier.

This pic is an MDF base for a jointer I'm building. It's a butt joint, with a routed chamfer, so you're looking at the edge of the MDF. Sealed with epoxy, sand, and two coats of hammered spray paint.

5. ## Re: Cheap DIY Router Challenge !!!

Nice job. So I take it that the epoxy must soak a ways into the MDF? That would certainly make it resistant to moisture. With MDF, a 8x8 gantry beam is quite affordable and unsurpassed in rigidity, per \$ spent.

The paint you chose makes it look industrial. What color?

6. ## Re: Cheap DIY Router Challenge !!!

Not so much onto the face.but it'll soak a lot into the edges. One heavy coat is enough, though. When it cures, and you sand it, it get's glass smooth and feels like plastic.

The paint is Rustoleum deep blue hammered. It looks more blue in person. They don't make that color anymore. I only have 1/2 can left.

7. ## Re: Cheap DIY Router Challenge !!!

Originally Posted by ger21
The paint is Rustoleum deep blue hammered. It looks more blue in person. They don't make that color anymore. I only have 1/2 can left.
Heh. I like the hammered metallic look.

Originally Posted by pippin88
To compare different models / materials you have to look at the numbers.
dmalicky is trying to coach people through the math and analysis http://www.cnczone.com/forums/diy-cn...cad-posts.html and http://www.cnczone.com/forums/diy-cn...05508-cnc.html. What a brilliant contribution. From post #36 of the first link dmalicky summarizes as follows:

In a real CNC, there are about 10 components that contribute to the total (aggregate) deflection-at-the-cutter and the stiffness-at-the-cutter:
1. Spindle and Tool
2. Z Car
3. Z Car Linear Bearings & Rails: the xls calculates this
4. Gantry Car
5. Gantry Car Linear Bearings & Rails: the xls calculates this, too
6. Gantry Tube: usually hard to calculate without a computer model like above
7. Gantry Uprights/Risers/Legs
8. Gantry Feet Bearings & Rails: a strategic design will cause these to have little cutter deflection compared to the other linear bearings.
9. Long Frame Tubes that support the long rails
10. The rest of the Frame, Bed, and Spoilboard
11. Workpiece: hmm, well that's 1 more than 10 components. The spot where the cutter contacts the work piece is actually the reference point for cutter deflections. An equal and opposite force of 100 lb is applied to the workpiece, and it deflects, too, but since it's not part of the machine I assume it is rigid. So we're back to 10 components.

For a target total stiffness-at-cutter, there are some posts in the archives on that. Summarized:
Efficient steel cutting: 60,000 lb/in http://www.cnczone.com/forums/mechan...tml#post916569
Efficient aluminum cutting: 20,000+ lb/in (~1/3 of steel, based on modulus)
Efficient wood cutting: 4,000+ lb/in (~1/5 of aluminum, based on modulus)

I think these metrics are needed for any machine you intend to purchase or build. Without them how exactly do you know what you're getting? What is the best upgrade path? Even this low end competition needs some form of analysis and measurement otherwise what exactly is being built and what is it good for? From my perspective this information and learning process is more valuable than the end result. For my own project I'm currently studying isotropic and orthotropic material models and how they apply to FEA analysis. Hopefully the FEA analysis leads to an estimation of total stiffness-at-cutter.

8. ## Re: Cheap DIY Router Challenge !!!

Originally Posted by Louis_Cannell
On a budget a conversion can take a lot of beating, after getting interested in CNC I decided first off to buy and convert a mini mill capable of handling a bit of steel as well as Aluminium, Wood, Plastics so purchased a Seig X1 Super LP super and set about a conversion with a bit of experience in 3d Printers Laser cutters/engravers it took me 12 hours start to finish and has been used succesfully since for stainless and mild steel, aluminium, acrylic, MDF, PLY, and is currently being used to build something with larger area. Conversion was 3 Axis TB6560 Driver Controller Board 1/16Microstep, 12-36V, 1.5A-3A,
3 57BYGH56-401A Single-Shaft Stepper Motors 1.26Nm/175oz-in 2.8A, 24V 10A power supply with a few short pieces of 2020 an old PC case 2 Stepper motor mounts, 2 GT2 pulleys & 200mm closed belt , 2 8mm couplings. using mill itself to prepare parts.

Total cost Â£580 for the mill new delivered with a few collets endmills and chuck.
Total cost for rest Â£100 from Aliexpress, plus a few odds and ends cable etc.

For a total of Â£680 or Â£700 max to allow odds I already had I reckon the machine although limited to 330 x 150 with 200mm plus on Z axis gives me more bang for my buck than anything else I have seen

It is limited by its 5000rpm 500w brushless motor and size but can manage Stainless (just about) Mild Steel I cut my T_nuts and made a few tools, Stainless I have cut a few 12mm Bars keyways/flats for connecting etc, Aluminium it eats for breakfast, Acrylic and Timber 5000rpm not ideal but enough and it doubles as a capable drill press. I think considering price is around that of a 3020 piece of chinese junk maybe a 3040 with double the base area 1/2 the height and probably 1/10th of the ability, it would be tough to beat value for money and it is a cheap cinese machine at the end of the day but it works well.

Modifications to machine are minimal I only drilled a few holes in some cast everything else is ready and could go back to fully manual in about an Hour doubt I have even voided the warranty.

What do you think.
This thread seems to have gone to sleep.

This mill conversion is a great way to get maximum capability for minimum Â£Â£Â£, assuming you don't need to route large sheets of wood. It will certainly help with making parts for a larger router!

I didn't see any mention of ballscrews, so how did you deal with backlash on the acme thread leadscrews?

9. ## Re: Cheap DIY Router Challenge !!!

Reviving this as I'm curious as well about the state of DIY vs BUY in 2018H2.

X6-200LUSB is US\$2,199.00 - says .0025 mm/step resolution and 0.05mm position accuracy
Shapeoko 3 ~ US\$1200 - doesnt mention resolution or position accuracy

is it possible to build a CNC as good as/surpassing X6-200LUSB for ~US\$1000?

10. ## Re: Cheap DIY Router Challenge !!!

I would say that you can build one for that price. Or at least they can with volume production. The difference is probably their profit margin.
I won't say that you cannot build one for 1K, but it would require some excellent deals on Ebay for precision parts and extrusions and well as electronics. I'd say you would have to work hard at it to keep to the budget that low. Sweat equity costs time too and everyone knows, time is money.

11. ## Re: Cheap DIY Router Challenge !!!

I built mine for around \$1.200. Cutting area about 24X36 and made out of MDF. I bought Acme lead screws, and purchased motors and drivers from Steppermotoronline. Controller is an Arduino Uno. I bought components as I got the \$\$ and built it over about a 6 month period I think. Not sure of the resolution...it's way more accurate than I need to cut out electric guitar parts!

Originally Posted by e97
Reviving this as I'm curious as well about the state of DIY vs BUY in 2018H2.

X6-200LUSB is US\$2,199.00 - says .0025 mm/step resolution and 0.05mm position accuracy
Shapeoko 3 ~ US\$1200 - doesnt mention resolution or position accuracy

is it possible to build a CNC as good as/surpassing X6-200LUSB for ~US\$1000?

12. ## Re: Cheap DIY Router Challenge !!!

New here ( I think I was around here 10 years ago but I forget the username). I've been mulling over a 2.5 axis 1/4 sheet PKM. Well - not really 2.5 axis, more like 2 axis + plunge. I've been intrigued by PKM's ever since I saw a Cartesian Parallel machine, and I liked that the sliding axes can be free running and all precision is constrained to rotary joints. I picked 2ft x 4ft as a target size as I'm space constrained, lower costs, and it's big enough to do a neck through bass guitar (not a burning project goal, just a reasonable sounding upper size limit based on my interests).

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