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View mski's profile

Does cast iron flex

by mski
posted 08-28-2017 03:58 PM


29 replies so far

View Loren's profile

Loren

10785 posts in 4562 days


#1 posted 08-28-2017 04:01 PM

It does flex.

View MrUnix's profile

MrUnix

8279 posts in 3114 days


#2 posted 08-28-2017 04:04 PM

Yup… cast iron will flex. Cast iron fences are notorious for it, and the fix is usually to set it on the floor between two 2×4’s and stomp on it :)

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View mski's profile

mski

442 posts in 4895 days


#3 posted 08-28-2017 04:07 PM

Ok a 8” long solid piece though, I know a long fence ok , but besides putting it in a press ?
Maybe ill try a vise

-- MARK IN BOB, So. CAL

View bbasiaga's profile

bbasiaga

1243 posts in 2910 days


#4 posted 08-28-2017 04:33 PM

I recall when I was in high school, the Smithsonian had a bar of steel hanging from the ceiling, with a rope ties to each end and a strain gauge on it. I think it was 6”in diameter and maybe 3 or 4 feet long. You could pull on both topes, and the strain gauge would tell you how much you were flexing it. I got a few tenths of a thousadth.i was not a body builder.

So yes, you can definitely flex your cast iron top

Brian

-- Part of engineering is to know when to put your calculator down and pick up your tools.

View JCamp's profile

JCamp

1243 posts in 1465 days


#5 posted 08-28-2017 04:57 PM

I have heard a lot of folks talk about table saw tops not being perfectly flat or having some bow in them. In general though I would believe that they are flat enough for most wood workers projects. I would think a 1/16th warp would be an extreme. For me if I can build with in a 1/16th I am pretty happy lol

-- Whatsoever thy hand findeth to do, do it with all thy might

View MrRon's profile

MrRon

5954 posts in 4158 days


#6 posted 08-28-2017 05:43 PM

I would never jump on a piece of cast iron to straighten it. Cast iron is very brittle and although every material has a certain amount of “elasticity”, cast iron has very little. As an example, scissors can be steel or cast iron. When I used to sharpen tools, I would get a pair of scissors to sharpen. Not knowing if it was steel or cast iron, I would attempt to bend one blade for better blade contact. It would snap letting me know it was cast iron.

View splintergroup's profile

splintergroup

4124 posts in 2137 days


#7 posted 08-28-2017 06:02 PM

It used to be that good cast iron tools (saws, mills, etc.) had their raw castings left outside for a year or so to “season” before being machined and finished. Cast iron takes time to settle down and temperature cycling speeds the process.

Now-a-days, most machine castings are machined and shipped out shortly after the casting is made. Results is warping, sometimes sever, sometimes barely noticeable. My 1999 Unisaw has a slight warp in the cast top extensions.

Yes, you can beat iron castings into a slightly different shape, but it takes some force and of course it tends to not be very elastic and will snap without much warning.

If the Griz won’t give you a new part, you can always take it to a machine shop and have them either grind it flat or sand it flat on a belt. The sanding is cheaper and gives quite good results.

View MrRon's profile

MrRon

5954 posts in 4158 days


#8 posted 08-30-2017 05:16 PM

Splintergroup is right about the seasoning of castings before machining. Good machine tools today will state “seasoned casting” in their brochure and the price will reflect that.

View Dark_Lightning's profile

Dark_Lightning

4236 posts in 4024 days


#9 posted 09-01-2017 02:17 AM

I used to work as a millwright, installing heavy machinery. It could take days to grout the floor and shim a machine so that the ways ran true. It even came down to having a conditioned space, if the accuracy requirement was high enough. Try leveling and truing the ways on an 18’ lathe bed, when the roll up door is open, where the machine and the concrete shift from the change in temperature from one end to the other. EVERYTHING flexes; it’s just a matter of degree.

-- Steven.......Random Orbital Nailer

View Andre's profile

Andre

3827 posts in 2721 days


#10 posted 09-01-2017 04:09 AM

When Temperature is involved I believe we are entering the realm of coefficient of expansion?
Short answer is yes Everything will flex to some degree! Except my views on certain subjects! :)

-- Lifting one end of the plank.

View bonesbr549's profile

bonesbr549

1588 posts in 3982 days


#11 posted 09-01-2017 01:37 PM

One thing i would ask how are you measuring? Is it possible your tool you are using to measure is not constant or moving? Second, when you say not flat, how much? Remember there are industry standards as to what is considered flat. For instance I found out, that most manufacturer’s consider .001-.003 per foot, is considered accpetable. I have a 12” Griz jointer and there are areas that are .001, low based on a feeler gauge and a precision 48” strait edge. Again, not impacting to final product.

-- Sooner or later Liberals run out of other people's money.

View mski's profile

mski

442 posts in 4895 days


#12 posted 09-02-2017 12:27 AM

bonesbr549,
The problem is the lip is at the leading edge of the outfeed table, when I run a board with a sharp square edge it catches.
The tables and fence are dead flat the outfeed lip is machined perfect to the table.
I have tried everything, the mallet trick is a joke.
Im beginning to think Grizzly is the same.
The rest of the machine is great , no vibration plenty of power, this makes it a $1600 boat anchor !
Splintergroup, I remember doing that to engine blocks.

-- MARK IN BOB, So. CAL

View Loren's profile

Loren

10785 posts in 4562 days


#13 posted 09-02-2017 12:42 AM

If the table is flat but the lip is bowed, you
should be able to lap the part flat.

Expecting perfection from Grizzly is a bit
optimistic at the prices they sell machines at.

View bonesbr549's profile

bonesbr549

1588 posts in 3982 days


#14 posted 09-02-2017 01:38 AM

Can you post a pic.

-- Sooner or later Liberals run out of other people's money.

View MrUnix's profile

MrUnix

8279 posts in 3114 days


#15 posted 09-02-2017 01:50 AM

You might find this Wiki article at the VM site an interesting read:

Flattening Cast Iron Surfaces
(in particular, the last section on scraping)

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View mski's profile

mski

442 posts in 4895 days


#16 posted 09-03-2017 12:09 AM

I dont expect perfection but my work shouldnt catch on the table, they sent me another lip this one looks flat Maybe !
This is what it looks like

http://i190.photobucket.com/albums/z27/mskiba2/Table.jpg?t=1504310652

The first lip they sent

http://i190.photobucket.com/albums/z27/mskiba2/GWLip1.jpg?t=1504310658
I about had it Ill look into the lapping if the new lip doesnt work
Thanks to all

-- MARK IN BOB, So. CAL

View SCOTSMAN's profile

SCOTSMAN

5849 posts in 4500 days


#17 posted 09-03-2017 05:32 PM

I read somewhere older companies used to cast products and then left them out in all weathers to settle, before bringing them in to clean up and use. The theory I believe was new casting could warp like wood and therefore that is why they were left to acclimatise to the environment hence settling in. Alistair

-- excuse my typing as I have a form of parkinsons disease

View mski's profile

mski

442 posts in 4895 days


#18 posted 09-04-2017 09:58 PM



I read somewhere older companies used to cast products and then left them out in all weathers to settle, before bringing them in to clean up and use. The theory I believe was new casting could warp like wood and therefore that is why they were left to acclimatise to the environment hence settling in. Alistair

- SCOTSMAN


Yea we used to do that to engine blocks, like wood they needed to equalize , this thing is too thick and short to flex into place,, I got a straight one finally from Grizz, so when I get time
Thanks

-- MARK IN BOB, So. CAL

View josephf's profile

josephf

217 posts in 3011 days


#19 posted 09-04-2017 10:46 PM

i never new cast would bend,i thought of it more of a crack or bust type material . seems like before you took it to a machine shop maybe just settle in and hit with a belt sander .what do you have to loose .

View ArtMann's profile

ArtMann

1483 posts in 1731 days


#20 posted 09-04-2017 10:53 PM

The reason cast iron band saws are becoming less popular compared by welded steel frame saws is they are stiffer and less likely to flex when tensioning a wide blade.

View TheFridge's profile

TheFridge

10861 posts in 2401 days


#21 posted 09-05-2017 12:49 AM

Slow and steady pressure. Cast iron is a live material like glass. Stresses will somewhat equalize I suppose.

Think of an old old log cabin w glass windows and how the glass can be thicker at the bottom.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View sstoner's profile

sstoner

13 posts in 1095 days


#22 posted 01-21-2018 12:55 PM

Hello
I have a chance to purchase a used Go490w
Are you happy with your jointer and does it seem to hold its adjustments after you set it up?
Thanks
Scott

View pontic's profile

pontic

804 posts in 1523 days


#23 posted 01-23-2018 12:01 AM

They can “season” cast iorn by heat cycling it before machining it.

-- Illigitimii non carburundum sum

View Dark_Lightning's profile

Dark_Lightning

4236 posts in 4024 days


#24 posted 01-23-2018 03:55 AM



They can “season” cast iorn by heat cycling it before machining it.

- pontic

Yes, and the cost of the part reflects that. Not that there is anything wrong with that- one only gets what one pays for. I have a really old contractor’s saw, made back when contractors must have had arms like Arnold Schwarzenegger. The top is flat within .004”. It’s old enough that I didn’t pay a ton of money for it, though.

-- Steven.......Random Orbital Nailer

View Mark's profile

Mark

1054 posts in 2889 days


#25 posted 01-23-2018 05:08 AM

long story short Mski…it’s Chinese cast iron. Don’t hope for too much.

-- Mark

View IantheTinker's profile

IantheTinker

285 posts in 1042 days


#26 posted 01-23-2018 05:16 AM

I have learned much about cast iron from reading the comments to this post. Thank you all for sharing and giving us newbs a chance to learn!

-- pensivewoodworker.com

View robscastle's profile

robscastle

7514 posts in 3119 days


#27 posted 01-23-2018 10:46 AM

Ian I hope you ignored the obvious wiki rubbish,
Some people are good at putting their mouth into gear without engaging the brain.

-- Regards Rob

View Redoak49's profile

Redoak49

4953 posts in 2903 days


#28 posted 01-23-2018 12:29 PM

I am sorry to say but glass does not creep under normal temperatures. Maybe at much higher temps but not at any normal temps. Cast iron may warp due to unbalanced stresses after machining. This is similar to wood moving after cutting or planing.

View pontic's profile

pontic

804 posts in 1523 days


#29 posted 01-24-2018 11:48 AM

That’s what heat cycling tries to remove. It actually increases the elastic modulus of cast iron.
Which is a good thing for tooling and machining. The Victorian era metalurgest use to pack peat or charcoal around the cast items and return them to the “Soaking oven” so the outer layer of iron could have a higher carbon content and thus a more polishable and machinable surface. Now they just do this with graphite powder and induction heat then continue the heat cycle on the conveyor belt. Less stress induced cracks and micro cracks occur when threading is done and grinding and milling is done.
The down side if you are a Chinese manufacturing Baron it that you have to have higher grade tooling to do the required machining demands for the customer and more labor spend on the polish and finish of the item. Thus they will push for a raw cast or what they call a “Ductile” cast product wherever they can. Cheaper for them, simple as that. Just like the Victorian Barons did in America in the 1900’s.
Now the big dealers like Jet, Powermatic, Grizzly(I think) use the heat treating and carbon “soaking” procedures to their castings before machining. Don’t know about HF and other brands.

-- Illigitimii non carburundum sum

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