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Does cast iron flex

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Forum topic by mski posted 08-28-2017 03:58 PM 924 views 0 times favorited 21 replies Add to Favorites Watch
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mski

439 posts in 3763 days


08-28-2017 03:58 PM

Hi All,
Question am I nuts or is Grizzly ?
I bought a GO490W jointer and the lip on the infeed table was crowned (2 piece table) . the lip was flush on the middle but low on the inside and outside, table flat and true.
When I reported the problem the Tech said to tighten 2 screws (there are 3) and use a mallet to flex or bend the lip and tighten the other screw to straighten the lip.
Now this lip is a solid cast iron 1 5/8 X 1 1/8 triangle with 3 holes for the fasteners. I don’t think it would flex.
Ive been back and fourth with them on this for over 2 months, they sent me a new lip that was dinged up on the table side and had a bent corner from being dropped.
The machine is perfect besides this.
Anyway your thoughts on this, just to make sure Im not crazy
Mark

-- MARK IN BOB, So. CAL


21 replies so far

View Loren's profile

Loren

9431 posts in 3430 days


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

It does flex.

View MrUnix's profile

MrUnix

5808 posts in 1981 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

439 posts in 3763 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

980 posts in 1778 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

416 posts in 333 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

4351 posts in 3026 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

1550 posts in 1005 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

4351 posts in 3026 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

2825 posts in 2891 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.

-- Random Orbital Nailer

View Andre's profile

Andre

1399 posts in 1588 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

1437 posts in 2849 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

439 posts in 3763 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

9431 posts in 3430 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

1437 posts in 2849 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

5808 posts in 1981 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

showing 1 through 15 of 21 replies

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