Hi pippin,
Yeah, that is a problem. If you have a fixed size then second hand or new old stock becomes too patchy to be useful.I scored a precision granite frame to use as my machine base - this has set the size of certain things and enforced a moving gantry design (thus needing two 800mm travel screws).
Craig
Mineral castings.The standard to measure the static characteristics of machine tool bed and other components is usually the rigidity of materials, that is, the minimum deformation under load. Under the same weight, the rigidity of iron castings is the same as that of mineral castings without considering the influence of shape.
Nice to meet everyone.
If you need mineral castings.You can contact me, my email:[email protected]
I'm from China,My company has produced a lot of products, small can reach 100KG, large can do 46 tons.
My English is very average and I don't know how to upload photos. Very reason to share my product with you.
I contacted BST Automation as well as Ball screw support,Ball screw nut bracket,Motor bracket,Coupling,Round linear guide-Well Precision Machinery Co.,Limited for linear rails and ball screws.
For me both seem dodgy. Both claim that HIWIN linear rail blocks do not have the accuracy level printed. The guy from Ball screw support,Ball screw nut bracket,Motor bracket,Coupling,Round linear guide-Well Precision Machinery Co.,Limited even told me that both C and H accuracy levels are same.
The actual photos shared by BST Automation does not have them printed. On the other hand, I have a couple of genuine(?) blocks I bought from Moore international in UK for a higher price which has the accuracy level printed as H.
Also, many of the e-bay sellers listings also show accuracy levels printed. For example:
https://www.ebay.co.uk/itm/225571854...IAAOSwZT1kW4ai
Back to square one
Photo of your block please
7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)
Please check here.
https://ae02.alicdn.com/kf/Af826fce1...c38349550F.jpg
my email
What products you need to do, you can go here to find it,https://grabcad.com/library/ma-miner...inear-motors-1
Forgive my poor English,I do not register the website in English.So what you need to know, you can email directly.I will get back to you as soon as possible.
I am about to put an order for many things such as spindle, servos, etc from china very soon. I got some quotes from alibaba for T-slot tables (700mm X 300mm X 50mm) with 6 X 14 sized T slots. Prices range from 450-500 for cast iron and around 100 more for steel. They say things are prcise to around .01 for 1000 mm. Steel used is Q235. I am thinking of ordering a steel one, but just wanted to see if there are things that I need to be aware of before ordering.
I was shopping for some steel plates today to get some idea about the cost.
What type of steel should I be using for plates in the casting where rails, motors, bearing are attached. Mild steel? High carbon steel? Die steel? Stainless steel (304)?
Hi Sus - Out of your list Mild Steel is fine. If you don't want it to rust S304 is good but more $$$ for material and harder to machine. Die steel and high carbon steel no need for the higher properties or cost. Peter
back when I was considering long steel bars for the rails I was to use Steel 1.0038 / S235JR, its cheap and its the steel used for square pipes so I wanted to use the same steel for everything. When it comes to stainless in germany we have two most popular designations V2A and V4A. V2A is a CrNi and V4A is a CrNiMo steel. the cheaper V2A should suffice for anything related to rails.
V2A are 1.4301, 1.4541 and 1.4307
V4A are 1.4401, 1.4571 and 1.4404.
Stainless Steel 304 / 1.4301 / X5CrNi18.10 Pete mentioned is also the most popular V2A.
Hi,
mild steel, anything else is a waste.
When I was a lad my grandfather would point to a piece of steel to be used in the next project and declare ' that is 90 ton axle steel'....like its the best steel in the world. He was referring to
hardened and tempered 4340. It has a tensile strength of 180ksi, and hence the 90 ton moniker, and is as tough as hell. Its still my go to steel when I need somthing tough and strong.
Ordinary mild steel has a tensile strength of 60ksi, so 1/3 that of 4340.....but it has the same Youngs modulus. This I still find counterintuitive but a steel which is three times
stronger but is the same stiffness.
When designing and building CNC machines the stresses are a vanishingly small percentage of the tensile strength of a material....we use big thick sections not for strength but
for stiffness. If you want to build a stiff machine then mild steel is just as good as a through hardened chrome-moly steel like 4340.
If you need a strong steel because of local forces like a high tensile thread or a gear or a highly loaded axle then 4140 is a nice step up from mild steel, and if your serious about strength then 4340, thereafter
you are into tool steels and you'll have to harden them.....not really a hobbyists procedure.
Craig
Thanks all! I am very much relieved now. Apart from mild steel, all other steel I checked are extremely expensive! High carbon steel is manageable if really needed. Mild steel is pretty cheap.
I have a concern about Mild steel's tendency for it to get corroded when exposed to water. Given that I will be using water for cooling while cutting, how do you handle that. I was told by the steel vendor that Mild steel and high carbon steel can get corroded.
Also, is cast iron a good choice for the T-table?
Hi Sus - 1) you can paint the surface any colour you like. Polka dots are popular around here 2) I have used this sort of product for machine bits and car panels in the past 3) Parkerising and blackening are possible as well they usually need a bath but I'm sure there's products out there that are brushable. Peter
https://boatcraft.com.au/information...o_mc1_info.php
https://janekits.com.au/product-cate...el-blackening/
Hi - Metal stiffness and strength are not related. Metals consist of many many grains held together with either friction or intergranular materials. The stiffness of the material is how the bulk material behaves when strained. The strength of a metal, say the yeild or proof strength is the strain at which the grains start to slip over each other. So the strength of a metal is how good the grains are held together whereas the stiffness is how the bulk material behaves.
take an aluminium pot, its nearly pure aluminium. Its Youngs modulus is the same as 7075-T6 material. But the 1000 alloy has a YS<50MPa whereas the 7075-T6 is over 500MPa. So if you load two identical beams, one 1000 and 0one 7075 they will both deflect the same until a certain load then the 1000 series will yield. The 7075 beam will yeild at 500/50=10x that load. 7075-T6 is a zinc alloy that has been solution heat treated to homogonise the mix, then quenched to freeze the mix, then aged to harden the billet. The hardening is various interalloys filling in the grain boundaries and gluing the grains together hence its high strength. When initially refined aluminium was more expensive than gold and it was used for cutlery by Royalty. Now we chuck it in the bin.... Peter
Hi,
If your really concerned just paint or treat with a tannate......but are your sure you need to?. I use flood coolant all the time, on every job other than a PCB, and none of the steel or cast iron is paintedI have a concern about Mild steel's tendency for it to get corroded when exposed to water. Given that I will be using water for cooling while cutting, how do you handle that.
or in anyway treated and it might get a rusty sheen, but that's about it. Worry about important stuff, not whether it will rust.
Craig
Hi,
grey cast iron has a Youngs modulus of 110GPa, various SG grades of cast iron have a Youngs modulus of 170GPa and steel has a modulus of 205GPa.
For a fixed and given size section steel will be stiffer than SG, and that will be stiffer than grey iron.
If designing a part you'll already know how stiff you want the part to be so you'd make a steel part with a certain thickness, and slighter thicker for SG and thicker again for grey iron.
The thickness is approximately proportional to the cube root of the modulus ratio.
steel 205GPa thickness T
SG Iron 170GPa
(205/170)1/3 . T = 1.06 T
Grey Iron 110GPa
(205/110)1/3 .T= 1.36 T
So despite grey cast iron only being half as stiff as steel it requires 36% greater thickness to match a steel part. Note these are 'seat of the pants' calculations, not the sort that you use for design,
but just to give you a feel for the scale of the problem.
Provided you are not constrained by dimension or weight then either cast iron or steel can be used. Cast iron has nice vibration damping properties which is a bonus, and of course if you are casting
then you get the exact shape and size you require. You can of course cast steel but its expensive, you've got into hard mold territory, and that costs bigtime. Other than that you have to construct steel
by welding which requires heat treating thereafter.
Craig
Hi,
if you use a water soluble oil in the coolant it pretty much eliminates rust......of course the best corrosion inhibitor is whale snot.
A friend of mine lives it Kiakoura and whales live there year round and there is a thriving business taking tourists out to see them. The whales get pissed off and hoink
up great big gobs of snot, and Roger collects it. Win...win!!
Craig