I have been a member for a year or so and don't like generalized questions,but will make one myself.
To be more specific.On a seriously large machine like Jerry fly guy or Madvac,is 3/16" or1/4" or whatever thickness steel tube sufficiently strong for threading for the linear rails?Would fine threads be in order?At what point or thickness would be overkill.Sorry for being so vague.
Larry

Gut feeling answer...fine thread, 3/16 wall thickness, attachment bolts every 4 to 6 inches, torqued to about 60% of the recommended maximum.

Overkill??? Anything above 1/4" wall thickness. Get your stiffness by building a truss structure much like the flyguy did.

Wow Geof,7minutes to reply.You must be on servos.Jerry is moving 1800lbs on steppers at decent speeds.Overkill [1/4"] is fine for me as the gantry should weigh in at 500lbs with a 7,5 horse colombo.[gut feeling answer]I like!!!Following paper calculations to the T can result in less than optimun results.Gut feelings from experience usually blow away paper.
The question aroused as I have HRW-21 and the supplied mounting bolts are t-n-weeny perhaps M-6 or so.I will bug you some more on Gut fellings later.
Thank you mucho!
Larry

How square is square?
I am a woodworker but have various pieces of steel about the shop.Checking 4'X4" steel angle it is far from square,ditto for channel.I see why or the purpose of epoxy joints to resist stressing the metal.Being the surface plate guy I assumed I could use S/P technology
to my advantage.Settling on 2-2by4's for the gantry spaced for a ballscrew in the middle I thought what a good thing to use the surface plate epoxy for accuracy.
The two by fours samples are flat and square and epoxy joints are unnessary.Is this just a fluke?Or is steel tube generally flatter and square than angles or channel?I half expected the 4" dimension to at least be bowed in.Perhaps when I file the order I will receive the inaccuracies I expected.
Are A36 tubes more accurate than other shapes?Gut felling answers are welcomed.
Larry...

Didn't make this one in 7 minutes due to being at a wine appreciation class.

What you should due for your tube is go and see if the supplier will let you check their stock and select the best; hollow structural steel can vary a lot. I have used many feet of 2" x 2" x1/8" and sometimes a shipment will be square to within better than .01" other times as bad as 1/16". We cut the tube into 2" lengths to make little bevel gear boxes so square is important which is why we measure it.

Like going to Home Depot and selecting the best 2X4's?I am sure the steel guys would laugh if I requested to sort out 20' 200lbs 2X4's.Hopefully I will get good "run of the mill"tubes and not require many epoxy joints.
I am amazed that members are hand drilling and tapping rail mounts with success.THK says the LM guides can absorb some miss alignment.How much I don't know,But perhaps this is why members are having good results by hand.I would assume if your machine is extremely rigid this requires extremely accurate drilling and tapping as the frame will not "give".
I have seen lots of alignment schemes with clamps and tools for rail trueness.If the mounting surface is milled or leveled with epoxy half the alignment problem is solved?True?If so a scribed centre line should be all that is needed to get a true master rail.
Larry

I have been a member for a year or so and don't like generalized questions,but will make one myself.
To be more specific.On a seriously large machine like Jerry fly guy or Madvac,is 3/16" or1/4" or whatever thickness steel tube sufficiently strong for threading for the linear rails?Would fine threads be in order?At what point or thickness would be overkill.Sorry for being so vague.
Larry

Larry,
Ideally the thickness of the piece to tap into should be equal to the bolt nominal size i.e 1/4 thick for 1/4-20 bolts etc... Worse case scenario is that you need to place Nutsert type inserts or self clinching nuts depending on how the drilled hole can be accessed.


Best regards

Bruno

Check this site out:

http://www.futek.com/boltcalc.aspx

It has saved me countless hours of calculations over the last few years.

Scott

Tubing thickness is important, but not so much for strength in this case. Smaller linear rails typically have ~60mm bolt spacing for rigidity rather than raw strength. Can't go wrong with thicker materials though. I'd go as thick as possible just for stability.

As for squareness, don't expect it to be square at all. Not quite as bad as aluminum extrusion, but not great either. Certainly not as bad as channel or angle. That stuff is garbage for anything non-structural.

Bolting/welding on an extra piece of flat bar to a tube (and either shimming or machining it flat) is a must if high accuracy and low friction is what you desire.

Thanks guys for all the help.These are questions to help fine tune a design for a 5X10 router.I have spent the last 8 months on the epoxy granite thread,Ignoring what I want to achieve.Unfortunately all the Zone threads and posts I saved over the year were lost.I would like to build with no welding,using epoxy joints and E/G where useful.
An absolute must is another axis or Y carriage for a drill.A CNC router without a drill is useless to me.Upon drafting a design,[no CAD skills]It appears the gantry would have to be 8'long to cut or drill a 5'sheet.Any cool ideas for a drill?Adding 3' to the gantry ups the cost considering the price of linear rails and ballscrew.If their is noway around it,so be it I will build an 8'gantry.
Thanks again
Larry

Larry,
Why add a drill, you could drill and cut with the router and a router bit that is the the size of the smallest diameter hole you need to make.

Me confused!!

Best regards

Bruno

Bruno, Confucius say:confused:"Baseball is wrong - man with four balls cannot walk"
Bruno,I am not CNC'd and have 2large Makita routers,2 monster porter cables and 2 makita trimmers.The idea is I don't like to change bits.One router cuts circles,one trims,one cuts from templates,one trims arborite etc.The bit or the smallist drill hole is 5/16 which in 18mm birch would probably result in 200ipm or less.Tool change is necessary at ten grand or at least a spindle and drill.My workers can blow away a CNC at 200ipm with a table saw and pin router.As a hobby router any ipm is sufficent as its cool or fun.A hundred grand router is so fast you have a guy just watching it to unload parts when finished.Hopefuly a hundred grand router can be self made for 20grand.
:cheers:gotta get back to the Bradors.
Merci Bruno
Larry

....A hundred grand router is so fast you have a guy just watching it to unload parts when finished.Hopefuly a hundred grand router can be self made for 20grand....

I think you are optimistic :) but JFG seems to have done something close.

But why do you need a hundred grand machine? A sixty five grand one can do things too fast for an operator to keep up; I had one for a few months but sold it to a friend with a millwork operation.

Geof,actually JFG gave me good advive in the past.Say it takes 45minutes to assemble a unit.If the router is slow,like 45 minutes to cut the parts you have perfect production.If cutting like 600ipm someone watches the machine and you get a pile of parts to store.I agree with JFG.I will try to design with comfort not speed which I assume is less costly.
Here is one of those generalized questions.If cutting at 600ipm and 1200 rapids,does one have to attend the machine at all times?If cutting slower is it possible for me to be assembling while the router does its thing?If cutting at moderate speeds is it less likely to miss steps or have to make a mad dash to E-Stop?
Thanks Geof
Larry

Here is one of those generalized questions.If cutting at 600ipm and 1200 rapids,does one have to attend the machine at all times?

If you're running one-off parts, then I'd say yes. If you're doing a production run, then after one or two parts, you should be able to let it run unattended. Although we normally run hundreds of unique parts a day, most of which take about a minute or so, when we have parts with long run times, we let the parts run and walk away. How comfortable you are with your programming plays a part when doing one-offs, but like I said, if it's the same part over and over, I'd let it go unattended.


If cutting slower is it possible for me to be assembling while the router does its thing?

This is basically the same question as the last one. If you are confident that the machine will cut the part without problems, then why stand and watch it?


If cutting at moderate speeds is it less likely to miss steps or have to make a mad dash to E-Stop?
Larry

If speed is causing lost steps, then you are underpowered, or not designed correctly. In a production environment, you should never have to even think about lost steps. I'd say design it to have 25-50% more power than you need. If you want your machine to act like a machine costing 5x as much, you need to design it like that machine.

As for the Estop, if something's wrong, no matter how fast you're going, it'll be too late by the time you get to the big red button. :) Your best defense is to keep your hand on the feedrate override if your worried. But speed alone isn't going to cause problems.
Jmho.

One other thing, Larry. Routers can make a lot of noise. I'd rather cut my parts twice as fast, and have half the day quiet, then have the router screaming next to me all day long. :)

Thanks gerry good points.The questions were related to visiting CNC shops with 100K machines.They always seem to have an attendent ready to vary the feed rate manually if it sounds strained.Doesn't sound very automation to me.
I totally agree,have half the day quiet although it's too late for me.I am deaf from 40years of screaming Makita routers.
Larry

When cutting wood sheet goods, you shouldn't need to be varying the feedrate. Occasionally for hardwood maybe, but unless you're trying to squeeze a little more life from a dull tool, you shouldn't have to touch it. A lot of it comes down to knowing what you're doing. The button pushers standing there watching the machine run probably don't know all that much about what they are doing. But these days, it's hard to find someone who really knows what they're doing, and then nobody wants to pay for someone that knows what they're doing.

May I interject a question? (I am going to anyway :) )

What are typical cycle times when doing bits and pieces for cabinet making on a commercial CNC router?

Few minutes, tens of minutes, hours or all over the place. My limited exposure to this type of stuff gave me the idea the cycle times tend to be too short to walk away from the machine and doing anything else of significance.

Gerry good points again,The points are on my head.(chair)
KNOWIN WHAT YAZ DOING costs $.I once hired a CNC trained guy with all the credentials for our non CNC shop.The guy didn't know how to use a hammer.Possibly a programmer doesn't have to know woodworking but a basic knowledge would be commendable.
Our only material is 18mmBaltic birch which is a challenge for most machines.The Larkin designer once said to me,in reality the material is so tough,2 passes are necessary.Gotta respect a machine builder not pushing the envelop to increase sales.
Larry

Geof my cycle times are 45 minutes on nested parts for a complex loudspeaker cabinet composed of 27 parts with rabbits and dadoes and drilled holes.I have no problem paying 85 bucks /hr but some day the contractor will be too busy to run my parts.Hopefully I can build a suitable machine and keep everything in house.
Larry

May I interject a question? (I am going to anyway :) )

What are typical cycle times when doing bits and pieces for cabinet making on a commercial CNC router?

Few minutes, tens of minutes, hours or all over the place. My limited exposure to this type of stuff gave me the idea the cycle times tend to be too short to walk away from the machine and doing anything else of significance.

Depends on the machine a little bit, which depends on the parts your making. A newer machining center, with maybe 15-20 vertical drilling spindles, and a few horizontal boring spindles, in addition to a small grooving saw and a router or two with tool changer, shouldn't take much more than a minute to do a cabinet side, which would consist of a notch for the toe base, a groove for the back, line bore for shelf pins, and drill for hinges and drawer slides, and maybe dowel holes.

But we also do a lot of custom millwork, and occasionally run parts that take 45min to an hour.

Shops doing nested based manufacturing, where they throw a full sheet on the router, and it cuts multiple parts from the sheet as well as all the drilling, might run 10-15 minutes for the sheet of parts.

Larry, is that 45 minutes a single 5x5 sheet? Or do you get it in 4x8s?

Gerry good points again,The points are on my head.(chair)
KNOWIN WHAT YAZ DOING costs $.I once hired a CNC trained guy with all the credentials for our non CNC shop.The guy didn't know how to use a hammer.Possibly a programmer doesn't have to know woodworking but a basic knowledge would be commendable.


I firmly believe that to be a good programmer (for woodworking), you need a pretty good knowledge of woodworking without cnc.


Our only material is 18mmBaltic birch which is a challenge for most machines.The Larkin designer once said to me,in reality the material is so tough,2 passes are necessary.Gotta respect a machine builder not pushing the envelop to increase sales.
Larry

Depends a little on your spindle and machine, but the right tooling makes all the difference. Not cheap, but something like this should do the job just fine.
http://www.vortextool.com/standard/productDetail.cfm?groupID=275

Gerry the posts are faster than I can type.I have been using 5X5 Russian birch for 30years.I remember paying 9bucks a sheet.Now it is $40 for 5X5 or $65 for 4X8.5X5 gives better yield for our purpose and to answer the question,it is 45 minutes on a 5X5 on a thermwood with 10 hp spindle.
BTW Russian birch is russian birch,not Baltic birch,Baltic birch was a disguise of Russian birch so Americans would buy it.BW,beware Chinese birch is micro birch skins on poplar core.The Chinese don't understand what crossbanding is.Sheets are generally received so warped they are usless even for crating.
Larry

larry & ger21;

Thanks. Those times are in the same range as what we do on metal bits and pieces; cycle times ranging from minutes to hours.

I had wondered because the machine I owned briefly had the ability to work in two zones with the operator loading one while the machine was processing the other. I had the image of some poor machine loader running like a maniac to keep up with what the machine was doing.

We can't use any of the chinese plywood, it warps so bad our vacuum can't hold it down. As soon as you cut the bands, too.

45 minutes sure seems like a long time to me. Are they drilling with the router? Or does it have drilling spindles?

Yep the router has drilling spindles which is done first.There is many drilled holes as they are the guides in assembly to locate the rabbits and dadoes for the screws.Actually the first run was done at 600ipm which had so much chatter it required countless hours of sanding edges.Going down to 400ipm resulted in perfect edges with no chatter.
Chinese birch is perfect for circular columns.Our distributer gave us HoChemIN birch free to try for crates.Free was not a good price.If they learn of crossbanding it will be a viable product.
BTW lifts of birch made in Lativa seem to be the best quality.
Larry

I had wondered because the machine I owned briefly had the ability to work in two zones with the operator loading one while the machine was processing the other. I had the image of some poor machine loader running like a maniac to keep up with what the machine was doing.

That's what we do. While one part is running, the operator grabs the next part, scans the barcoded label which loads the program for that part, then loads the part. Then unload the finished part, and repeat for the other zone. The tricky part is to get an equal number of parts for each zone, to keep the machine running constantly.

We don't build to stock sizes, everything is custom, so most parts have their own unique programs. Without barcoding, it would be almost impossible to get the correct program for the part.