Funny Dovetail

[cnc2]

Hi guys !

I've been inspired by the design shown here

I'm a beginner non machinist & don't know how to use Solidworks yet (i'm having troubles with my graphics).

You can see my idea in the drawing below it's a very basic/crappy MS Paint drawing... i hope you'll understand !

I want to make the bearings of the right side adjustable by excentric for preload but will have to mod the design a bit...Any help ?

I don't know the effect of hardned steel bearings rolling on an iron dovetail, i'm thinking to use grey iron machined from solid. What do you think ?
How much will it cost in a basic machine shop ? (aprox price or expensive/lowcost or hours of work)

I want to build a cnc knee mill the size of an X2/X3 and use this design for XYZ, the mill will be cast aluminium. What do you think ?

The cool thing about this design is that you can lengthen/shorten it to suite your needs, IMHO.


Any input is much apreciated.

Thanks !

cnc2.

[keebler303]

I think a lot of hobbyists greatly underestimate the cost of getting parts made at a machine shop. For the cost of your intended design, I would bet you can buy some linear rails and blocks for about the same cost. These will give you a better and more durable machine without so much aggravation.

One example of decently priced rails:

http://www.homeshopcnc.com/LinearGuide2.html

Matt

[cnc2]

Thanks for your reply Matt !

I know about ready made linear rails & wanted to buy brand new HiWin linear rails from automation4less.com they have resonable pricing but, when i checked the shipping fees the price was doubled BECAUSE I'm outside of USA & very far from there...No one comming from USA to bring'em to me, not talking about the size & weight of 6 rails & 12 blocks.

I want to build a cnc knee mill the size of an X3 & want to use this funny dovetail design for XYZ one wide rail per axis with a heavy & long block(will cast it myself) with maybe 4 rows of bearings rolling on each side of the iron dovetail.

Will the bearings have a lamination effect on the dovetail & wear it out quickly ?
What do you think ?

Thanks !

cnc2.

[keebler303]

I don't think your design is very good for durability or stiffness. I assume you want to be able to machine metal. The design you are "inspired" by does not look to be used for metal cutting, and as such can be much lighter.

There are hundreds of places to buy linear rails, maybe some close to you. If you specified your location as something a bit more specific than the planet you inhabit, maybe I could suggest an alternative source.

Matt

[ckirchen]

Originally Posted by cnc2 I'm outside of USA & very far from there.

Well, we are you located? "Earth" is clever but really doesn't give us much to go on when offering advice.

I agree with Matt, stock parts are often the best solution. Also, it is much easier to buy another in the event of a failure. i.e. What happens if part of your custom design wears out? You have to get another one made = $$$. If it was a stock part, you will probably spend much less.

There must be a source for linear rails in or close to your country; let us know where you're at and I'm sure someone could point you in the right direction.

Chris Kirchen

EDIT: Sorry for the double scolding about your location; Matt must be a faster typer than me

[cnc2]

It's ok you don't have to be sorry Chris !

"Earth" is clever but really doesn't give us much to go on when offering advice

:

Well, i'm in Algiers, Algeria & i defy you to find a linear rails supplier in here. (who knows if you succeed i also need a supplier for servos or i'll be obliged to go with photocopier servos)


I also agree with the idea of ready made linear rail & all the hassle it will save me(not sure it's good english) but getting HiWins for double their price will cost as much as a ready made X3 buying a ready made X3 will also double its price, no supplier in here too.

All the automation shops in here sell only pneumatic equipment, i asked for a ball screw in a shop that had a big Festo sign at its door and the guy an old machinist told me we sell "automation parts" if you want a screw the hardware store is rigth there in the corner : then i said no it's not a simple screw it's especially used in automation... to believe me he took a big catalog...in fact it does exist aahh but it not used in here the market needs pneumatic spare parts so, that's what we offer...even if you want to buy it or you could order it, it would be VERY expensive (more than if i order it & pay shippment from a foreign country) it's industrial supplys it's intended for factories...too expensive for you...blablabla.

I found a "linear stage" but made from extruded aluminium with a built in hydraulic cylinder and the rail on it had plastic where balls should be rolling & was not intended to sustain any lateral loads...it was 80cm long, used and for aprox 350Euros.

Automation in here still means rough pick&place used in food industries & cnc shops can be counted on the fingers of the thumb i heared some Airbus parts were made in here so, those few cnc shops won't talk to the little guy.


Thanks for you help !

cnc2.

[cnc2]

Originally Posted by keebler303 I don't think your design is very good for durability or stiffness. I assume you want to be able to machine metal. The design you are "inspired" by does not look to be used for metal cutting, and as such can be much lighter. There are hundreds of places to buy linear rails, maybe some close to you. If you specified your location as something a bit more specific than the planet you inhabit, maybe I could suggest an alternative source. Matt

Sorry Matt ididn't see your post !

Yea i want it to machine metal, for stiffness the iron dovetail will be 100mm wide or so & there will be one per axis. This will require to have the lead screws aside the main rail but should be ok.

Close countries, maybe Germany or France, my biggest problem is shipping, it costs a LOT +CUSTOMS, and you can't be sure to recive you package.

Sombody i know was comming from Germany for holidays & he brought me the UHU chips from Uli Huber & the electronics from reichelt.de...that's how i got the electronics, if Uli had sent me the chips by mail i might'd never recived 'em.

Linear rails are heavy weight the size is also a problem, i couldn't ask someone comming for holidays to bring me a ~15 kg package, so i'm stuck !

Thanks !

cnc2.

[ckirchen]

You might want to contact HiWin and some of the other automation component manufacturers and ask them who you closest distributor is.

When I built my first machine, I sourced the ball screws and ball nuts through a automation company. The parts weren't part of what they regularly sold, but it was in one of their supplier's catalog. They were overpriced and the attitude of the staff was poor; they must have felt that they were doing me a huge favor.

A couple of months later, I found out from Thompson's head office that there was another distributor in my area. When I went to talk to them, it was a completely different experience. The staff was courteous and pleasant, and the parts were about 30% to 40% cheaper. Maybe it was because they sold these parts all the time.

All I'm saying is that you might need to find the right shop to buy from.

[cnc2]

Originally Posted by ckirchen You might want to contact HiWin and some of the other automation component manufacturers and ask them who you closest distributor is. When I built my first machine, I sourced the ball screws and ball nuts through a automation company. The parts weren't part of what they regularly sold, but it was in one of their supplier's catalog. They were overpriced and the attitude of the staff was poor; they must have felt that they were doing me a huge favor. A couple of months later, I found out from Thompson's head office that there was another distributor in my area. When I went to talk to them, it was a completely different experience. The staff was courteous and pleasant, and the parts were about 30% to 40% cheaper. Maybe it was because they sold these parts all the time. All I'm saying is that you might need to find the right shop to buy from.

Thanks for the reply Chris !

The HiWin website has changed, on the old one there was no supplier in North Africa nor there is in the new one. In their new website the nearest HiWin plant is in Germany & there's no sellers network on it i think you're right about mailing'em. i also looked on hiwin worldwide and they directed me to the german plant.

My BIGGEST problem is shipping, packages are often lost when you ain't a big importation company with transit agents, not to talk about customs on ~700eur worth package. Even if i find someone comming from germany the package will be big & heavy...who can accept this ?

Even if i find someone that accepts to bring me that package, i'll sitll need a webstore to see the prices & order the parts for the guy to pay'em from there (like i did with reichelt.de for the electronics).

Will mail'em & see.

Thanks !

cnc2.

[cnc2]

Hello, Dear staff, I saw many american webstores that are selling HiWin products where you can see products prices & order online, but i couldn't find any german webstore selling HiWin products to the public in Germany. The nearest HiWin plant to me is in Germany, as i don't read/speak german, would you please point me to a german webstore that supports the english language, where i can see the prices & order the parts online ? I am interrested in linear guideways, so please point me to a webstore that sells to the public & at public intended prices. Many thanks !

That was my email info@hiwin.de...what do you think about it ?
I need you advise because i'm used to forum english & my english isn't that good & i have to impove it. So please tell me the naked truth !

Thanks !

cnc2.

[ckirchen]

Originally Posted by cnc2 That was my email info@hiwin.de ...what do you think about it ?

I would mention to them where you are located. Even though it appears as if the German webstore is the closest to you, there may be a local distributor that you don't know about. The local distributor will have the pull to be able to ensure that shipment does not get lost or loaded up with excessive customs fees. In the eyes of customs and the freight company, you are a one-time importer, and may get treated differently than a seasoned importer, such as a local distributor. Though, you will have to cover the distributor's customs and freight fees, but if your parts are part of a larger shipment, they will be much less than what you would pay by yourself.

You're in Algiers; a distributor in your town would be great, but anywhere in Algeria is still good. Unless the customs laws are radically different there, you don't have to pay customs fees if the package doesn't cross a country's border.

Chris Kirchen

[cnc2]

Thanks for the reply Chris !

You're right, i forgot the main point.

I wrote an email to info@hiwin.com asking'em for the closest supplier to me in here...i was waiting for a reply & forgot it was the weekend.

Thanks !

cnc2.