Fixed gantry or column for mill rigidity?

[JRoque]

Hi all,

Making all those insert armatures etc is too labour intensive for production

and I don't know about you but there's no way I can plan ahead for every possible location I will ever need an insert placed. I like the idea of being able to drill and tap where/when actually needed.

prefer being able to be poured into mould dry

How does that work? How does it infuse later? Probably not heat as it would require quite a bit of it. Also, being poured and tamped down to dimensions probably means you can add anything to it later to solidify it as the dimensions would change. Also, what's "steel shot"? Boy, I really need to read up on these new processes :-)

Regards,
JR

[peteeng]

Hi JR - Infusion is a process where you have a "closed" mould or a vacuum bagged mould. You stack dry cloth, timber, sand, sawdust whatever you like into the mould then evacuate the volume. You then use the vacuum to draw in resin and fill the void. This does a few things 1) It fills the void entirely if done correctly 2) the vacuum removes water vapour from the matrix which is a big inhibitor to epoxy sticking to the matrix and water vapour or dew is on everything generally. You can see the vapour coming our of the pump... It also applies 1 atm pressure to the pack 10tonne / sm so you consolidate packs very well. Do searches on composite infusion. For epoxy granite you don't need a super dooper vac pump either as its quite porous compared to doing a CF laminate for instance.




Please note PVA used as a release is not the carpenters glue!! White glue should be called PVAc if you look it up. Glue is poly vinyl acetate whereas release is Poly vinyl alcohol... it is impermeable to gases so various outgassing and desorbtion and mould stick ups don't occur.

Steel shot is used in grit blasting and is available in various sizes and types. Being steel its modulus is 200GPa which is 3x more then sand so the resulting polymer concrete or epoxy granite is 3x stiff. Its also heavy so you get a good mass addition if you want. The photo of the filled mould shows the filling marks over a period of about 15mins. I have done a 50ft boat some years ago that used 400kg of resin over a 1 hr period to fill. So size does not matter. You will need a very thin infusion epoxy, a laminating epoxy will only travel a short distance.

You could use sand and other ceramics but I want to be able to post machine parts in my router so I need a material that machines easily. Do a search for Tetrium-S this is something I make at the moment or Tetrium-A.

Infusion has many names but it is now the preferred process in aerospace. Its called an "out of autoclave process" It allows huge structures to be made without an autoclave which saves a huge amount of time and $$$. Cheers Peter

https://www.eit.edu.au/cms/news/indu...ineering-award

[JRoque]

Very impressive, Peter! I figured you were experimenting with this stuff but you're clearly a pro at it. A 50' infused boat?? wow :-) Very much looking forward to your design and material use/process.

Cheers,
JR

[peteeng]

Hi JR - I've been infusing things for over 20 years. Have trained many boatbuilders, tank builders and others to infuse. Great process. Will make excellent machine parts. Attached is a 70m mast I was involved with some 20 years ago. The main mast 70m and mizzen 50m were built in an autoclave (for a large superyacht). We infused the booms (12m and 15m long) but I can't find any photos of it. Was routine at the time so didn't take many photos... Cheers Peter

Found some of a 45ft monohull hull I was involved in 15 years ago. I didn't like the plumbing, too complex but I wasn't in charge of that. I think it was 3x200kg drums of resin in this lot in one hit. Recent work has been in industrial composites, power poles, elevated work platforms, tooling board and auto parts. Now I want to build really good router and mill parts.

[awerby]

Are these improved router and mill parts just for your personal use, or are you planning a commercial venture with them?

[peteeng]

Hi Awerby - Look up cncrouterkits.com.au. I have been developing a business for a couple of years figuring out where the market is and how to respond to it. A picture is emerging. Peter

[awerby]

Too bad you're so far away, or I'd order a composite gantry beam in Tetrium for the new machine I've been dreaming about. What would something like that cost, about 2 meters long?

[peteeng]

Hi Awerby - Freight costs have gone up with Covid but if you send me a specification of what you want eg the dimensions and say equivalent steel or aluminium size then I can figure it out. PM me. Peter

[peteeng]

Hi Andrew- Have a look at this thread. Peter

https://www.cnczone.com/forums/uncat...iomimicry.html

[peteeng]

Hi All- Maybe interesting for people - Webinar on infusion. Peter

https://register.gotowebinar.com/reg...892?source=web

[JRoque]

Hi Peter, much appreciated! That's all above my pay grade. I can barely hacksaw through steel :-)

Speaking of which, I ordered some steel plates and started trying to plane them on my Bridgeport. That machine barely qualifies as a drill. The table see-saws up/down when I go over the midpoint of travel. I was wondering why my fly cutter was leaving two distinct cut patterns across the work piece. Bottom line, I need to redo the ways or find a way of using my old CNC router, straight edges and surfaces to plane and square the parts. The fun factor just jumped 10-fold.. ha!

Regards,
JR

[mactec54]

Hi Peter, much appreciated! That's all above my pay grade. I can barely hacksaw through steel :-)

Speaking of which, I ordered some steel plates and started trying to plane them on my Bridgeport. That machine barely qualifies as a drill. The table see-saws up/down when I go over the midpoint of travel. I was wondering why my fly cutter was leaving two distinct cut patterns across the work piece. Bottom line, I need to redo the ways or find a way of using my old CNC router, straight edges and surfaces to plane and square the parts. The fun factor just jumped 10-fold.. ha!

Regards,
JR

There are gibs that you can adjust to help with some of the slop in your old Bridgeport, do a search on how to, if you don't know what to do, the head Tramming is also important to get a flat surface

[JRoque]

Hi Matec,

Yes, I've seen the gibs. They are adjusted to the max. When that wasn't enough, the previous owner brazed an additional piece to push it in even more. Both axes flop about until you lock them.

I bought thicker, tapered gibs that are used to eek out a few more years out of these machines, but this one's done. The ways are dished in deep. The screws are worn out in parts so even if the gibs were tight, it would not be able to hold a position that well. Too bad because I spent months restoring everything else. It's a pretty good drill, though

Regards,
JR

[awerby]

It sounds like you need to find another Bridgeport with a good base but a bad head (assuming yours is in good shape).

[JRoque]

Exactly right! I've tried but there's nothing nearby that's any good. I bought this one locally after the seller described it as in "good shape". It's a good boat anchor.. ha! The local ones are all fixer uppers as well. The head in mine is indeed in good shape as I put a lot of effort and parts into that.

That's how this thread started. I want to build a machine to replace the BP. Maybe I should just reuse the base, knee, ram, etc and build a CNC around that rather than trying to fix or convert it. The column would make a sturdy support for sure.

Regards,
JR

[awerby]

If the ways are really shot, you might be able to mount some beefy linear rails in their place; there are plenty of newer mills that use them instead of the older style of ways. Then replace the wonky leadscrew with a ball screw and you're off to the races with that boat...

[JRoque]

Hi Andrew,

Yes, I've been looking into that as well. Of course, I would have to true the ways somehow before mounting the rails. Perhaps I can cheat some and shim under the rails, especially if it's just to restore the BP sufficiently just so it helps with the new CNC build. Decisions, decisions.... The rails/shim option seems plausible. Thanks for the ideas, please keep them coming.

Thanks,
JR

[peteeng]

HI JR & others - has anyone tried rebuilding ways with epoxy/ceramic mixtures? See WR-2 in the Devon range...Regards Peter
https://itwperformancepolymers.com/products/devcon

[RubeG]

Hi JR, have you considered using products such as Turcite, Garlock or Rulon to repair the Bridgeport ways? Won't help with the worn screws but might be an option to extend the machine life.

[JRoque]

Hi all, and thanks for the suggestions. Those sent me on an information gathering tour and it's great to see more options. The good thing about using these is that I can do my grinding on the added surface, rather than further removing material form the ways.

If all else fails and I can't find a local place to machine the columns flat, I may end up building a rig directly on my table (which *is* flat) and use a guided grinder for the job. And if a pig flies and somehow that works, I could also use it to make the Bridgeport a mill again.

I started buying some of the materials for the CNC but they are on the Coronavirus slow boat. I really hope things get better for obvious reasons but also because I'd hate have to wait around 3 or 4 weeks for some piece to come in. The spindle motor and controller should be here by the end of this week.

Regards,
JR