New Router

[johnm99]

Well...
I am about to begin my first router... I will be using JGRO's plans.... However, I would like to modify them a little and I have some questions I would like to throw out here first.

First of all... I would like to extend my table to 48" x 48"... my question is will there be problems with the gas pipe flexing over this span? I think I read something about this in some thread. If so can someone recommend an alternative that is cost considerate.

2nd, I have heard that the MDF is a little more suitable than plywood due to relative humidities and moisture content. Is this so?

and would there be a real problem with using Hardwood ply.? I was able to get 3 sheets for free, thats why i ask.

So far thats where I am at.. have planned on using acme screws since they seem to be cheaper than ball screws... with the xylotex board and 280 oz steppers...

Do you guys see any problems with this... please head me off at the pass if you do....

Will post pics as they come....

[ger21]

THere's a reason you don't see many large size machines built with gas pipe. Unless you can support it somehow, it will flex. Cost effective is a relative term, but unfortunately, there isn't a cheap alternative. Your best bet would try to find some good quality stuff on Ebay. You need to be really patient to get the best deals, though.

Plywood will work just as well as MDF, but you may find that it will warp easier. Once painted or sealed, either should be OK. I see you're in the south. High humidity will swell MDF, so seal it with shellac or a good primer before it has a chance.

Acme screws are fine. Good quality acme leadscrews can be found at http://www.mscdirect.com for decent prices. Much better than cheap acme threaded rod, imo.

[Popeye]

Why couldn't you fill the pipe with fiberglass reinforced concrete? Cheap and very rigid.
IMHO

[DieGuy]

This thread shows one method of supporting the gas pipe with the torrsion box, I think one thing that was suggested was to use a v instead of a rounded cutout. Or an exact size cutout to match the pipe. Thsi one seems to have used the knowledge used to improve on the original design and allow for longer pipe runs.

Second MDF machine

[johnm99]

I think I will try the torsion box idea.. A little added support should take the flex out...


also about MSCdirect... Leadscrews Vs. threaded Rod.... I can only find the Threaded rod listed... whats the difference there????

Back to the saws...!

[ger21]

Originally Posted by Popeye Why couldn't you fill the pipe with fiberglass reinforced concrete? Cheap and very rigid. IMHO

Not rigid enough. ANY flex is too much.

[ger21]

Originally Posted by johnm99 I think I will try the torsion box idea.. A little added support should take the flex out... also about MSCdirect... Leadscrews Vs. threaded Rod.... I can only find the Threaded rod listed... whats the difference there???? Back to the saws...!

The leadscrews are manufactured to higher tolerances. I can't check right now, their website is down for maintenance. The screws manufactured by Nook are leadscrews, and the Keystone screws which I think are on the previous page.

[johnm99]

I have my table and gantry cut.... Will be posting some pics when I get a little further on assembly...

Quick questions...
cold roll vs. gas pipe... is one better than the other... I know any flex is no good...but i figure CR to be harder and more durable... just getting the opinion of the forum...

Also I am rethinking the motors I was going to purchase due to funds...
Is there some kind of guide out there on the size of steppers I would need... to push this size of machine... I am/was considering the 276 oz on AD(automationdirect) but could purchase sooner if I could get some cheaper...

thanks again!

[rweatherly]

CR vs. Gas Pipe: I am not sure that the hardness is that different, in fact the gas pipe may be slightly harder. The important advantages of CR are:

-Better surface finish and dimentional tolerance . Gas pipe is actually made from a flat strip that is rolled into a pipe shape and welded, so there is quite a bit of dimensional variation in diameter. That said, the variation of gas pipe along the length is not too bad. You can get seamless pipe, at a higher price, but you need to go to a pipe supplier for that.

-Less deflection. Since it is solid, it will deflect less than a hollow. For 1" pipe, which is 1.315 OD and 1.097 ID, the deflection for CR is about half that of gas pipe. You can offset the defection problem by supporting the pipe or CR along the length.

The big advantage of gas pipe is that it is inexpensive. You can always change it to CR or drill rod at a later date. For my machine (using gas pipe for now), the problem is in the flexure of the structure.

Richard

[ViperTX]

Actually Gas Pipe has a more consistent finish....the other pipe is galvanized and the surface is not as consistent.

[rweatherly]

I guess "gas" pipe may be too generic. What they use for gas pipe around here is steel pipe that has a black coating (which can be sanded off). The galvanized version of the same basic pipe is used for water service. (Galvanized is not used for gas, since it has a tendency to flake off & clog up gas pilots)

In any case, what you get could (and probably will be) different from location to location.

[johnm99]

So it seems i should try the Gas pipe 1st and then get upgrade to the CR if desired... I plan on using some type of support anywany to keep from flexing.

The only thing I have seen in hardware stores in my area is the galvanized.

Thanks for your suggestions.