Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Quote:
Originally Posted by
ger21
That claims .015% per 1% of moisture content change for baltic birch (finnish birch).
MDF is .05%, which means it shrinks and grows 3x more than baltic birch.
Any wood construction should be sealed as well as possible, which will greatly reduce movement.
i use a sealant on wood but the issues for me usually arise from the moisture that is already in there. The walnut stock blanks I buy can be considered dry enough to use when moisture gets down to 6%. I have never seen any with 0%.
It's not really an issue on a deer rifle. It's a big deal for me though because I use the stocks as master plugs when making rigid molds (for carbon fiber). If the wood expands, even a little, it either gets stuck in the mold or the mold cracks. Or, I have indexing issues when I make the second mold half.
I have gotten around thus issue by making resin castings in silicone before making the rigid molds. Now that my cnc machine is up and running though, it would be nice to be able to use wood directly. I am going to order some Baltic Birch this week to try.
1 Attachment(s)
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Attachment 422760
I built this machine to cut wood, aluminum and mild steel.
The frame and gantry are steel, the Z axis is mostly MIC6 aluminum.
The X and Y axis are chain drive and the Z axis is ball screw.
I use linear ball bearings everywhere.
I can cut up to 22" x 14" and I hold repeatable tolerances of 0.002"
This is all custom made and the final tally was just under $4,000.
All the parts are purchased from eBay, amazon and automation direct.
I can change the spindle from the mill head (pictured) to a router head.
My free travel speed is 300 in/min (I've had it up to 600)
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Very nice machine!
Quote:
Originally Posted by
atomictow
Attachment 422760
I built this machine to cut wood, aluminum and mild steel.
The frame and gantry are steel, the Z axis is mostly MIC6 aluminum.
The X and Y axis are chain drive and the Z axis is ball screw.
I use linear ball bearings everywhere.
I can cut up to 22" x 14" and I hold repeatable tolerances of 0.002"
This is all custom made and the final tally was just under $4,000.
All the parts are purchased from eBay, amazon and automation direct.
I can change the spindle from the mill head (pictured) to a router head.
My free travel speed is 300 in/min (I've had it up to 600)
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Given that you can pick up used Bridgeports starting at $2000 (for a working one), I think it is always worth starting with an honest appraisal of whether you can really make something better than what you could buy for the same cash.
With a budget of $4000, given the choice, I probably would have gone for a used 9 x 42 Bridgeport ($2000), a cheap (ish) cnc electronics set ($1000 for 3 axis) and used the remaining $1000 for a power drawbar or maybe a used speeder.
Don't get me wrong, I like what I have built, it was a fun project, I just wish I would have known then what I know now. Making your first cnc machine takes ages and it is certainly not a given that you can make something cheaper that you could buy it for (on the used market).
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
….Are you saying that a Bridgeport with Acme screws and dovetails and having an R8 head with a quill and belt drive is the way to go?
Firstly, if the well used Bridgey has any wear on the dovetails that makes it a has been and having a quill with belt drive too...….not my cup of tea.
For a start the sheer size of it will make most people wilt at the prospect of pulling it apart.
I think there is a distinct dividing line where hobby work ends and commercial work begins and a Bridgeport retrofit is not a good choice in either case.
The topic, BTW, is about a router system for close tolerances so a Bridgeport is not in that league at all, it's a mill.
Ian.
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Hello Gaemon - To stabilise wood you can plasticise it with epoxy. Look up the infusion process. If you have a good vacuum pump you place the timber or wood into a vacuum bag pull it down to under the local water saturation pressure, boil off all the water in the wood (takes say 1hr) then introduce infusion epoxy to the end grain (while still in the bag) and it soaks up the epoxy like water hence filling all the pores. You then let it cure and its about twice as dense and won't move on you ever. A little post cure helps. Wood is half air so all the pores that usually carry water carry thin epoxy really well. I have also done this with large blocks of MDF to turn it into tooling board. I've also done it with mdf sawdust to make tooling board. I'm about to make a block of recycled jeans and some carbon fibre into a solid slab for a friend that makes knives for making handles.... Good process. Peter
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Hmmmm...………..without going to all that bother I'd rather just mix up a whole load of fine sawdust and mix it with epoxy then cast it in a wood box mould that's probably more like what a DIY approach would be like.
At the same time you could make a steel frame work to make it more rigid and add a series of tapped holes, then cast the epoxy mix around it......I doubt that would move even if it was dunked in water.
Ian.
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Hi Ian - If you have a vacuum pump its actually easier then mixing sawdust as you suggest and the result is several orders of magnitude better. Adding steel frames to compensate for warping is counterproductive if the intent is for a tool board. Metal framing just creates lots of internal stress... The easiest path is to buy premade tooling board but generally its expensive and Makers like making. Peter
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Quote:
Originally Posted by
handlewanker
….Are you saying that a Bridgeport with Acme screws and dovetails and having an R8 head with a quill and belt drive is the way to go?
Firstly, if the well used Bridgey has any wear on the dovetails that makes it a has been and having a quill with belt drive too...….not my cup of tea.
For a start the sheer size of it will make most people wilt at the prospect of pulling it apart.
I think there is a distinct dividing line where hobby work ends and commercial work begins and a Bridgeport retrofit is not a good choice in either case.
The topic, BTW, is about a router system for close tolerances so a Bridgeport is not in that league at all, it's a mill.
Ian.
It obviously depends on what you plan to cut and how much travel you need.
My point was that, whatever your needs, it is worth checking to see what used machinery you can find for the same money before going the diy route. Most people here are simply not capable of building a diy machine base that can match the precision of used industrial kit.
Obviously, if you need 12 feet of X axis travel then you'd look for a used router instead of a mill. There is no need to get hung up on the distinction if you are doing a retro-fit project though. Once you have acquired a sturdy and precise machine base, you can just install the right type of spindle and motors for the type of work.
In terms of size and bulk, I am not sure there is any line between hobby and work machines. I have seen some enormous diy cnc routers here. A 9 x 42 Bridgeport is certainly chunky but not that different to a medium size cnc router in terms of footprint.
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Quote:
Originally Posted by
peteeng
Hello Gaemon - To stabilise wood you can plasticise it with epoxy. Look up the infusion process. If you have a good vacuum pump you place the timber or wood into a vacuum bag pull it down to under the local water saturation pressure, boil off all the water in the wood (takes say 1hr) then introduce infusion epoxy to the end grain (while still in the bag) and it soaks up the epoxy like water hence filling all the pores. You then let it cure and its about twice as dense and won't move on you ever. A little post cure helps. Wood is half air so all the pores that usually carry water carry thin epoxy really well. I have also done this with large blocks of MDF to turn it into tooling board. I've also done it with mdf sawdust to make tooling board. I'm about to make a block of recycled jeans and some carbon fibre into a solid slab for a friend that makes knives for making handles.... Good process. Peter
That all sounds like more hassle and money than it is worth. If I am going to add epoxy to something, It would be better to add it to carbon fiber or fiberglass.
Unless the layer of epoxy is very thick (like as thick as the wood) I doubt you achieve a satisfactory increase in stiffness anyway. I've seen wood expand or bow and break epoxy shells a number of times. 1\4" of epoxy spread over a medium to large area would snap like a twig with mild pressure.
Sand and gravel is a far better filler for epoxy than sawdust BTW. Home Depot sells 50lb bags of sand and gravel for around $5.
Re: How is everyone building a DIY CNC router system that maintains cutting tolerance
Hi Gaemon - The idea is to make something you can machine. For instance your stocks or moulds. It's not to increases stiffness its to make it stable. Effectively its tooling board. Have you seen or used tooling board? Peter
Tooling Boards – Meury Enterprises
