CNC ROUTER TABLE FLATNESS

[mactec54]

I am located in the UK.

First any reasonably low cost frame will twist upon installation.
If the frame twists whilst being moved then I agree that machining the rail surfaces will be pointless. I think it would be easy enough to check this doesn't happen prior to getting it machined. A lighter cheaper material might as well be used if this is the case.

The second item is your concern that machining the spoil board will just curve it to match the imperfections in the machine. This is very true. However even if you have perfect rail mounting surfaces you still need to flatten the spoil board.

Alternatively if you are thinking of not machining a spoilboard, or making any other compomises, I would no longer call it a router

I did plan on machining the spoil board or aluminium bed but my point is the rails need to be flat and level before doing this.

I agree that milling the surface would be good enough as opposed to grinding.

Can anyone offer any pointers on De-stressing the frame. Is this something that can be done DIY or does it need out sourcing.

Cheers

You should have a lot of options being in the UK look for someone that has a Planer Mill there has to be lots of them, a lot of these machines originated in the UK

To stress relieve the frame there are 2 main method's that work there is a vibratory process or Heat treating both methods work well, or you could throw it outside for 2 years or so, this is how they used to do castings and some still do

As for twist if you have any twist by moving a small frame like this them you have not built / designed it correctly, large frames can twist that is why machines have adjuster on the feet of the machine, the mounting pads on the bottom of your frame is the first part to machine, then this is the datum face that sits on the machine to machine the top and sides if you where doing any mounting on the sides

Build a rigid structure and you won't have a problem

[routalot]

Its good to see another Brit building,or at least planning,a new machine.I have a few things I don't fully understand about the project and would like to ask a few questions to help me comprehend the choices that have been made.Would I be correct in assuming the size is partly determined by the workshop space available?I understand the likelihood of welding inducing an amount of distortion and the challenge of arriving at a flat surface.My question would be how much welding do you need to hold the machine together in view of the loads that would be imposed versus how much welding could you apply?I'm not enough of a welder to advise on tacking and optimum weld sequence,but there has to be a strategy that would minimise distortion.

The design in the first post is clearly some way from finished and could easily stand on top of a base frame with built in adjustment.It also needs a gantry and might I suggest completing the design before cutting or welding anything?Its so much easier to amend things at the stage when they are still on screen rather than cutting pieces of steel off or welding them on.

[mactec54]

Its good to see another Brit building,or at least planning,a new machine.I have a few things I don't fully understand about the project and would like to ask a few questions to help me comprehend the choices that have been made.Would I be correct in assuming the size is partly determined by the workshop space available?I understand the likelihood of welding inducing an amount of distortion and the challenge of arriving at a flat surface.My question would be how much welding do you need to hold the machine together in view of the loads that would be imposed versus how much welding could you apply?I'm not enough of a welder to advise on tacking and optimum weld sequence,but there has to be a strategy that would minimise distortion.

The design in the first post is clearly some way from finished and could easily stand on top of a base frame with built in adjustment.It also needs a gantry and might I suggest completing the design before cutting or welding anything?Its so much easier to amend things at the stage when they are still on screen rather than cutting pieces of steel off or welding them on.

His frame he has is all he needs at this point it is how this frame is put together is the important part it going to have distortion no matter how he welds it, although it can be minimized by knowing how to construct with welding of the frame

It still will need machining if you use linear rails so does not matter about the distortion from welding, alignment is more important when he is constructing this design

[wizard]

Epoxy is totally useless for linear rail mounting, you obvious have never done it or even tried it

I wasn’t commenting on epoxy leveling usefulness but rather that guys look for low cost ways to avoid machining. You may consider it useless and frankly I’m not all that excited by it but that doesn’t mean it won’t work.

As for using epoxy the only uses I’ve had for it recently is in grouting and the use of Moglice on plain bearing machines. Also anchor setting. But no use for leveling yet, I will not dismiss it though especially when guys in this forum have had success. Epoxy is just like any other material, used properly you can get good results.

The costs to Grind something like this can be less than to mill the surfaces, lot less setup time to Blanchard Grind something like this

I guess that depends upon the shop and the tools they have available to them. Setup time on a large horizontal can be well under an hour, probably less than 15 minutes. I can’t think of any automation machinery we have had ground in recent memory. The only thing ground I can think of was on plain ways on specialized grinders.

In any event my point that I was trying to make is that the original posters quest for precision will blow the cost of his build out of the water. This especially when he has already expressed reluctance to pay the going rate.

[mactec54]

I wasn’t commenting on epoxy leveling usefulness but rather that guys look for low cost ways to avoid machining. You may consider it useless and frankly I’m not all that excited by it but that doesn’t mean it won’t work.

As for using epoxy the only uses I’ve had for it recently is in grouting and the use of Moglice on plain bearing machines. Also anchor setting. But no use for leveling yet, I will not dismiss it though especially when guys in this forum have had success. Epoxy is just like any other material, used properly you can get good results.


I guess that depends upon the shop and the tools they have available to them. Setup time on a large horizontal can be well under an hour, probably less than 15 minutes. I can’t think of any automation machinery we have had ground in recent memory. The only thing ground I can think of was on plain ways on specialized grinders.

In any event my point that I was trying to make is that the original posters quest for precision will blow the cost of his build out of the water. This especially when he has already expressed reluctance to pay the going rate.

They say they have had success some of us no different, they most likely have noting to accurately check the rail for straightness and flatness

The original post has nothing to do with precision although he may have mentioned it, it's how he can mount Linear Rails and the only way is to machine , scrap, or grind

I guarantee there are none that have been successful in reality, when torqueing the rail bolts the rail sinks into the epoxy, I don't call that successful even if it only moved .0001" which I found was .004' to .005" of squish into the epoxy, so that would not be worth doing it, the cost is not very much to machine something like he wants to do, I have tried the Moglice and the rail sinks into it as well and that is way harder than normal epoxy, the Moglice would be more expensive than machining to do that much surface area, he could do his table with epoxy and machine the 2 rail mounting surfaces which would be very basic to do

[hughes674]

Hi All

Thanks for your comments.
I have found a company who can grind or mill this for around £400 but the size is close to there capacity. The thread was started to see if there was an alternative to having to do this and still end up with something that would have good tolerances. Ideally I would like to make the bed bigger as the cost for doing so would not be much more but I know now that getting this ground would be extremely difficult.
I totally appreciate that using the square linear rails need to be fitted onto a ground or machined surface.

Would it work to use perhaps 100 x 30mm ground flat bar on top of the tubular frame and shim out any deflection in the flatness of the bar before fitting the rails. I cant imagine there being much deflection in something of this gauge.
Obviously I would bolt this rather than welding it to eliminate distortion.

Earlier in the thread I sort of dismissed the use of a spirit levels but after further research found there are engineers levels which are accurate to 0.01mm/m. (Apologies my ignorance. Just a builder for my main job).
If this method could work I don't see why using a level of this accuracy could not put everything on a good enough plane before machining the router bed.



Cheers
Mick

[wmgeorge]

Sure you can put a 3 or 4 inch (100 mm) wide piece of cold rolled steel maybe 12 mm thick on top of your rails shim and true as needed. But the 400 British pounds or $650 US is not not out of line for grinding both rails, at least I don't think anyway. There are ways to mount a linear rail and make it adjustable. You can get creative. Only you can decide on is the final cost really worth it?

Epoxy? Maybe if your a professional and know what your doing and have success in the past, AND for a DIY job it sounds like an easy way out. Do some research as suggested and try to find some DIY success stories.

[mactec54]

Hi All

Thanks for your comments.
I have found a company who can grind or mill this for around £400 but the size is close to there capacity. The thread was started to see if there was an alternative to having to do this and still end up with something that would have good tolerances. Ideally I would like to make the bed bigger as the cost for doing so would not be much more but I know now that getting this ground would be extremely difficult.
I totally appreciate that using the square linear rails need to be fitted onto a ground or machined surface.

Would it work to use perhaps 100 x 30mm ground flat bar on top of the tubular frame and shim out any deflection in the flatness of the bar before fitting the rails. I cant imagine there being much deflection in something of this gauge.
Obviously I would bolt this rather than welding it to eliminate distortion.

Earlier in the thread I sort of dismissed the use of a spirit levels but after further research found there are engineers levels which are accurate to 0.01mm/m. (Apologies my ignorance. Just a builder for my main job).
If this method could work I don't see why using a level of this accuracy could not put everything on a good enough plane before machining the router bed.



Cheers
Mick

Machinist levels and master precision level are used by everyone that is installing new machines or machine builders, or moving old machines to somewhere new, they are very different to the levels they were referring to which were the levels you get from the hardware store that you see most hubby guys using

Could you use ground bar, you could but the size you are talking about would cost near the same as having your top machined, which the price you quoted is more than it should be, just machine where the rails are to be mounted and use epoxy for the table ground bar that size is not that flat either, check out the tolerance spec's per foot

[wmgeorge]

You don't Have to mount the Linear Rail system on top, it can be on the side where it can be adjusted up and down, IF needed like this custom made Camaster machine video shows. Built for a Camaster management team member.

[Bravin Neff]

Easy peasy. Find a boring mill shop. One with an 80" devlieg. I don't know where you are, but there probably a dozen around me within 10 miles. Often $75/hour shop rate. Machining those rails and the bed would be a couple hour job including setup.

[Ntl]

Easy peasy. Find a boring mill shop. One with an 80" devlieg. I don't know where you are, but there probably a dozen around me within 10 miles. Often $75/hour shop rate. Machining those rails and the bed would be a couple hour job including setup.

Whew where you at in the US that is still running a $75hr shop rate? Not in SoCal unless you're buddies with the owner and the shop is slow. That's what we were paying 10 years ago around here. I'm just curious what the rates are like outside of our area.

[jono5axe]

Regarding epoxy for leveling beds for linear rails.

1) My experience with this was unsatisfactory. Checking results with my precision level, straight edges, feeler gauges, etc, I found the results to be not very flat at all. If you want to get some sort of flat and level outcome then I would say that the pour needs to be min 5 or 6mm deep. The longer the bed the deeper. But I don't know this for certain.

2) Regarding epoxy changing shape under bolt-down torque, the hardness values for epoxy are available and can be compared to other materials, for example aluminium, and then a person can make their decision whether this is sufficient. From memory I believe that epoxy is approx 1/3 the hardness of Al (annealed) ? I would think that the epoxy would probably flog out sooner or later.

3) Epoxy is not a cheap material. I would say that the epoxy costs are not insignificant compared to machining costs. And the whole setup process is a time consuming (pain in the a) exercise.

[routalot]

I think the solution you propose in post #26 is probably the easiest solution.In fact I doubt you would really need ground steel,cold rolled would probably be accurate enough for most purposes although it might offend those who work on components for nuclear reactors or atomic clocks.A really good level and a long straight edge would be valuable things to have.I have seen rails that were poorly installed in that they had a 0.3mm sag over a 2 metre length and the gantry still ran and a careful builder should be able to do much better than that.

Having got one set of rails in place,how do you propose to get he rest in place?

[Bravin Neff]

Whew where you at in the US that is still running a $75hr shop rate? Not in SoCal unless you're buddies with the owner and the shop is slow. That's what we were paying 10 years ago around here. I'm just curious what the rates are like outside of our area.

Maybe it's a hundred bucks. An 80" devlieg is at least 40 years old, and costs very little. But one in decent shape will hold those flatness and parallels better than 0.0005". The point is that it's well within reach to get those surfaces machined adequately for linear rails.

[mactec54]

Maybe it's a hundred bucks. An 80" devlieg is at least 40 years old, and costs very little. But one in decent shape will hold those flatness and parallels better than 0.0005". The point is that it's well within reach to get those surfaces machined adequately for linear rails.

Good to see someone else on the same page

[mactec54]

Regarding epoxy for leveling beds for linear rails.

1) My experience with this was unsatisfactory. Checking results with my precision level, straight edges, feeler gauges, etc, I found the results to be not very flat at all. If you want to get some sort of flat and level outcome then I would say that the pour needs to be min 5 or 6mm deep. The longer the bed the deeper. But I don't know this for certain.

2) Regarding epoxy changing shape under bolt-down torque, the hardness values for epoxy are available and can be compared to other materials, for example aluminium, and then a person can make their decision whether this is sufficient. From memory I believe that epoxy is approx 1/3 the hardness of Al (annealed) ? I would think that the epoxy would probably flog out sooner or later.

3) Epoxy is not a cheap material. I would say that the epoxy costs are not insignificant compared to machining costs. And the whole setup process is a time consuming (pain in the a) exercise.

A good post from someone with experience in doing this, everyone should check out jone5axe build

[wmgeorge]

Maybe it's a hundred bucks. An 80" devlieg is at least 40 years old, and costs very little. But one in decent shape will hold those flatness and parallels better than 0.0005". The point is that it's well within reach to get those surfaces machined adequately for linear rails.

You have a machine shop that can fit the entire machine in, after welding and true the top rails and the bed? A $100 shop rate is cheap, don't forget the setup time is going to be billed out also. Post the name of that shop maybe others would use it?

How is this machine going to mill or grind the table of a welded up frame, where the rails are 10 inches or more above the table?

[mactec54]

You have a machine shop that can fit the entire machine in, after welding and true the top rails and the bed? A $100 shop rate is cheap, don't forget the setup time is going to be billed out also. Post the name of that shop maybe others would use it?

How is this machine going to mill or grind the table of a welded up frame, where the rails are 10 inches or more above the table?

That's a horizontal they don't only make horizontal machines and that is a small one as well, but could still machine the tops of the up stands 20" above the table, and then machine the table, they fit a 90 degree head, the table on these machines rotates

Do you think this is big enough these machines are everywhere gathering dust in most shops

[wmgeorge]

Well I wish these folks who know where these big machines are at will post their location? From aside from Mactec54 no one else has done so. Thanks Mac and that location should be good for a lot of people. Well I need to go to the shop and make some money.

[mactec54]

Well I wish these folks who know where these big machines are at will post their location? From aside from Mactec54 no one else has done so. Thanks Mac and that location should be good for a lot of people. Well I need to go to the shop and make some money.

Most people don't know what to look for, every large city in the USA will have these large machine so they are out there and every where around the world, here is someone's dream router frame being machined