# What the heck?



## DavidR8 (Jan 22, 2020)

I sent an email to Shars telling them that the backplate in the 4-jaw chuck & backplate package is not well matched. 

The counterbores for the mounting bolts are too large which means that when you turn down the outside diameter to match the chuck, the edges of the counterbores are exposed. 

Below is their response:

“David
The OD of the backplate is not designed to be turned down due to the bolt circle pattern. The bolt circle is a set dimension that can not be changed on the chuck and the relationship between the chuck and back plate requires the OD of the back plate to be larger than the chuck.”

The backplate is advertised as being 6.3” in diameter. Naturally I assumed that was to allow for finishing the outside diameter to exactly match the chuck. 

Apparently I was wrong. Now I wonder if I have weakened the backplate. 



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## markba633csi (Jan 22, 2020)

One thing I have noticed about that outfit, they are good at excuses
I had a time with them over some poorly made jaws


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## francist (Jan 22, 2020)

I've never seen a mounted chuck that didn't have a backplate turned to match -- that's just goofy. Not saying it could not occur, but I don't think anybody could look at it and think 'oh yeah, you're supposed to leave the back plate larger like that...' .

As for weakening it, I doubt that you did although I suppose technically the lack of integrity on a contiguous perimeter would weaken something like that. Significantly weaken it, I'm doubting it but I am by no means an expert. I really didn't like the fact that you ended up with the open-sided holes though (dubbed "cheese grater" in another post) -- that didn't sit right with me for the reason given.

Scenarios like this are far from uncommon these days with parts made to fit multiple variants of the same piece. You end up with a one-size-fits-all mentality that cuts costs in manufacture but leaves the consumer holding a less than ideal product at the end.

-frank


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## macardoso (Jan 22, 2020)

My 3-jaw that was on my lathe when I bought it has a 6.3" backplate on a 6" chuck. I wouldn't worry about weakening it but if you don't like the finish, just replace the back plate. Shouldn't be expensive. 

Typically you only need to finish the front face and pilot diameter.

Sorry that happened to you. I've found Shars to be very responsive to issues whenever I've talked with them.


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## DavidR8 (Jan 22, 2020)

My response to them was this:
“I have never seen a backplate that did not to match the chuck diameter. 

My point is that the counterbores are too large. Were they smaller there wouldn’t be a problem. 
I suggest that the item description be changed so that it explicitly says not to turn down the outer diameter.”

I’ll fill them with some JB weld and call it good. Or I might fill the holes completely and turn the backplate 90 degrees and drill new holes with smaller counterbores. 



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## macardoso (Jan 22, 2020)

You can see the backplate protrudes from the edges of the chuck in this picture. Never found it annoying. Import chuck made in 93'


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## DavidR8 (Jan 22, 2020)

macardoso said:


> You can see the backplate protrudes from the edges of the chuck in this picture. Never found it annoying. Import chuck made in 93'
> 
> View attachment 311433



That much I could deal with but this was 3 tenths of an inch bigger. 
I wish I’d taken a picture. 


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## Shootymacshootface (Jan 22, 2020)

I think that you are correct about the not ideal matchup. Please make sure that there aren't any sharp edges left on the exposed counterbores. Bumping your hand on that part of the chuck would be no different than touching a live cutting tool.


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## Cadillac (Jan 22, 2020)

The only problem I see with cutting into the counterbore is now you have little knife edges around the chuck. If you run your hand on the chuck to slow it down when turned off you can now get caught by one of those pieces which could be ugly.


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## DavidR8 (Jan 22, 2020)

Thanks @Cadillac that's also my concern. When I get a bit of time I think my plan will be:


Use the backplate to make a hole pattern
Fill the existing holes
Drill new holes 90 degrees  using the pattern
Drill new small counterbores


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## middle.road (Jan 22, 2020)

DavidR8 said:


> That much I could deal with but this was 3 tenths of an inch bigger.
> I wish I’d taken a picture.
> 
> 
> Sent from my iPhone using Tapatalk


Suggestion: start taking pictures of all that you're doing. Do you have an unused phone laying around? Use that for photos in the shop so as not to risk your daily phone.
Give us a list of what you bought, the chuck it went on - details. Let's see what's what.
Pictures help to figure out the situ.


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## DavidR8 (Jan 22, 2020)

middle.road said:


> Suggestion: start taking pictures of all that you're doing. Do you have an unused phone laying around? Use that for photos in the shop so as not to risk your daily phone.
> Give us a list of what you bought, the chuck it went on - details. Let's see what's what.
> Pictures help to figure out the situ.


Will do!


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## mikey (Jan 22, 2020)

Their design is faulty if cutting the plate to match the diameter of the chuck results in a sharp edge and potential for injury. When I get a stupid response from an underling I go straight to the President of the company and let him/her know that if I am injured as a result of their poor design then I would be very unhappy. That usually results in memos flying all over the place and my problem is usually resolved to my satisfaction. Don't accept an unreasonable response from the support dept; go over them.


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## macardoso (Jan 22, 2020)

I agree the backplate not matching the chuck diameter would be super annoying, but if they don't direct you to cut the outside diameter to the chuck size then I would unfortunately argue that it isn't their fault. Bad design perhaps. Just a bit of an unfortunate situation.


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## Aaron_W (Jan 22, 2020)

I got backplates from little machineshop. The only downside is that they are not predrilled for the chuck, so you have to drill and tap your own holes. Good quality plates and if the holes to match up you can only blame yourself.

LMS is primarily focused on mini-lathes but they to carry a lot of stuff for 10" lathes. I have had no issues with anything I've bought from them.

Shars is ok, but issues are not unknown.


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## DavidR8 (Jan 22, 2020)

macardoso said:


> I agree the backplate not matching the chuck diameter would be super annoying, but if they don't direct you to cut the outside diameter to the chuck size then I would unfortunately argue that it isn't their fault. Bad design perhaps. Just a bit of an unfortunate situation.


There instructions are expressly about turning the register. They don't mention anything about the diameter though I expect they will update they based on my feedback.





__





						6" 4 Jaw Independent Lathe Chuck With 1-1/2 x 8 Threaded Mounting Plate
					

<!-- <ul><li>Chuck diameter: 6"</li><li>Thickness: 2.559"</li><li>Center hole: 1.575"</li><li>Back mounting: Plain back</li><li>Bolt Circle Diameter: 5.709"</li><li>Internal Jaw Clamping Range: 0.315" - 3.149"</li><li>External Jaw Clamping Range: 1.969" -




					www.shars.com


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## middle.road (Jan 22, 2020)

Let's see the chuck, the back plate, and how it mounts first before getting all up in arms with first tier customer support.

These (3) are for my 1440. Look at the one that is currently mounted. Bolt heads in the open.
Need to watch then when operating. The 3-jaw removable jaws one in the second photo has the cap screws recessed, and the 4-jaw has the mounting screws coming from the front.


	

		
			
		

		
	
...
	

		
			
		

		
	



Then on the small 3-jaw for my Logan take a look at how close the c'bores came to the outer edge.


	

		
			
		

		
	
...


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## francist (Jan 22, 2020)

One lesson to be learned here -- regardless of who may or may not be at fault -- is you gotta be aware of where you're cutting. Too easy to get all absorbed in how nicely the chips are coming off, you need to know your measurements and what happens as you near them. Kind of like hitting the faceplate screws at the bottom of the bowl or running a boring bar through until you hit the chuck jaws .....


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## middle.road (Jan 22, 2020)

DavidR8 said:


> There instructions are expressly about turning the register. They don't mention anything about the diameter though I expect they will update they based on my feedback.
> 
> 
> 
> ...


Did the bolts holes, (qty 4) line up correctly?
- What is the diameter of the counter-bore in the back plate measuring?
- Also need the center thru hole diameter dimension. Is it 1.57" or 2.16"?
On their drawings in their catalog they show 
m10's for the 202-6579 
and 
m8's for the 202-6579*a*
But then also - they're showing a drawing of a front mount chuck...
Something is not quite right here. Their drawings aren't quite in sync with the item.
Going off the link you posted the drawing calls for m8's.
I'm wondering if the c'bores are for m10's possibly.
Post some picts of the piece when you can.


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## MrWhoopee (Jan 22, 2020)

Rather than JB Weld, I might suggest press-fit sleeves for the counterbores (perhaps with Loctite) and then take another cut to clean them off flush with the OD.


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## Holescreek (Jan 22, 2020)

Look closely at the back edge of this Buck chuck:







I got a great deal (free) on a 6" adjust-tru with no backplate and found one with the same oversize condition you have.  Rather than using the original holes in the backplate I rotated the backplate hole pattern and made my own mounting holes then filled the originals with JB weld.  Once mounted on the chuck I turned the extra metal off  leaving the exposed JB weld segments.   That was about 15 years ago and I use the chuck nearly every day.  Don't underestimate JB Weld.


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## Ken from ontario (Jan 22, 2020)

In my opinion before resorting to JBweld or any other ideas you have in mind, bite the bullet and order another properly sized packplate that will fit  your chuck , I know it's extra expense but this is a hobby for you and should not be a source of aggravation, plus you can always use the new one as your template and/or a tool to measure your machining prowess by comparing it to the one you're fixing .

I know LMS (as arron-W ) mentioned may have exactly what you need 
Just a thought.


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## DavidR8 (Jan 22, 2020)

@francist I absolutely agree. I knew it was going to be close. :-(

@Ken from ontario I might just do that. I'm going to take some photos and detailed measurements tonight.

@middle.road Everything lined up perfectly. Keen eyes on the bolt sizes. Sitting at my desk I'm betting they are M10.
I searched for 202-6579A and there is no product. What I received is definitely a 202-6579.
This is the relevant line from my invoice.



Looking at the details I found this:




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						6" 3 jaw Self Centering Scroll Lathe Chucks 2 Piece Jaws with 1-1/2-8" Fully Machined Threaded Back Plate
					

Shars Tool




					www.shars.com
				



It is a 6" self-centring 3-jaw that uses the same backing plate as my 4-jaw.
This one mounts with M8 cap screws.
In the reviews there's a photo of a completed setup. The backing plate is turned to the chuck diameter and there's no breakout of the counter-bores. My assumption is that the M8 counter-bores are small enough that they are not exposed when turned to diameter.


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## Cadillac (Jan 22, 2020)

I've bought two d1-4 back plates from CDCO and if I remember correctly with shipping they were the cheapest. I know shars shipping prices are on the high side. Back plates were of good quality and fitment didn't have to adjust D taper for correct register to spindle. Actually have to tap chuck to release after pins are released.


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## f350ca (Jan 22, 2020)

I've had chucks where the back plate was slightly larger than the chuck body to cover the counter bores. Not Shars fault that the bolt circle on the chuck requires a larger backing plate.
On the extreme side, I wanted a smaller 4 jaw fir the Summit. The 16 inch will only close to 1 inch. Some one gave me a D1-8 back plate that was probably part of an integral mounted 3 jaw ? Faced off a lot of material to get the face down to mount an 8 inch one. 






I could take some material off the OD but if I took it to the size of the chuck there would only be 1/8 th of an inch left past the mounting pins.

Greg


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## middle.road (Jan 22, 2020)

If the 4-jaw is using m10's from the backside then that's why the C'Bores broke through. Even m8's are very close to the chuck body.
Grab a picture of the back side of the 4-jaw with a scale laying on it if you can.
If I'm reading the charts correctly, then:


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## DavidR8 (Jan 22, 2020)

@middle.road that looks to be exactly the right dimensions and about how much of the counter-bore is exposed.
Looks like an M10 has a 16mm head so .75mm clearance if I'm interpreting the drawing and cap screw specs correctly.


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## Bob Korves (Jan 22, 2020)

DavidR8 said:


> The backplate is advertised as being 6.3” in diameter. Naturally I assumed that was to allow for finishing the outside diameter to exactly match the chuck.


David, I have several older chucks to fit threaded spindles that are considerably SMALLER in diameter than the diameter of the chuck O. D.  None of that seems to matter much if you can get the two pieces mounted together solidly and without compromising the integrity of the chuck and the back plate.  With what you have done, I hope you did not leave sharp (or even close to sharp) edges that will bite you if your hands touch them.  I would heavily round the sharp points to a decent size radius to eliminate that danger.  Pics?


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## DavidR8 (Jan 22, 2020)

Here’s what I have. 
I do need to pull the cap screws, clean up and deburr the edges. 

That is an M10 cap screw. 
The counterbore is 17.75 mm
The head of the cap screw is 14.85 mm
So the counterbore is certainly larger than it needed to be. 

I wish I had quit while I was ahead 















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## Shootymacshootface (Jan 22, 2020)

If this was my situation I would remove the entire edge of the backplate that contains the counterbores. Make a step there and just have the bolt heads exposed. You could change to a different style bolt head, like a button head. This would be as safe as the chuck itself. The other option it to buy another backplate for a do over, and use the current one for a smaller chuck. A 3-4" or even a collet chuck.


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## middle.road (Jan 22, 2020)

Like my pictures above, 1st one that's on the lathe presently.
Else put a large chamfer on it.
I vote for the former.


Pull that screw out and get us some dimensions in SAE and Metric.
Something isn't right here. and the head Dia. of 14.85mm doesn't match anything that I can find.
That's too large of a counter-bore for that screw. - Shars is going to need to see that.


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## higgite (Jan 22, 2020)

I'm thinking maybe what you got from Shars is a truly 6" chuck paired with a nominal 6" (160mm) backplate. I've seen so called 6" chucks and backplates that are actually 160mm (6.3"). They sometimes round off whole mm sizes to the nearest inch. My 4 jaw is actually 100mm but masquerades as a 4". It can get confusing. But, with that said, it does sound like you got a backplate intended for use with M10 capscrews and a chuck with M8 holes. That's not a cheap backplate, pushing $70 if I remember right. I think I would call Shars again. Everybody has a boss, ask to speak him. Or her.  

Tom


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## DavidR8 (Jan 22, 2020)

It is an M10 cap screw.
The head of the cap screw is 14.75 mm or .58"
The counterbore is 17.75 mm or .70"


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## Flyinfool (Jan 22, 2020)

Since we are hobbyists we are always looking for something to make.
How about making A cup washer that will be a very close fit to the bolts you have, and the OD a press fit into the back plate. Make the bottom thin enough so that the bolt head will not stick out the back. Once you press these into place and tighten a bolt down on it they will not move. You can then turn down the OD of the face plate. And no one will ever see what you did.


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## DavidR8 (Jan 22, 2020)

higgite said:


> I'm thinking maybe what you got from Shars is a truly 6" chuck paired with a nominal 6" (160mm) backplate. I've seen so called 6" chucks and backplates that are actually 160mm (6.3"). They sometimes round off whole mm sizes to the nearest inch. My 4 jaw is actually 100mm but masquerades as a 4". It can get confusing. But, with that said, it does sound like you got a backplate intended for use with M10 capscrews and a chuck with M8 holes. That's not a cheap backplate, pushing $70 if I remember right. I think I would call Shars again. Everybody has a boss, ask to speak him. Or her.
> 
> Tom


Indeed the backplate is advertised as 6.3" listed for $67.95.

So something is up. I bought them as a package:




__





						6" 4 Jaw Independent Lathe Chuck With 1-1/2 x 8 Threaded Mounting Plate
					

<!-- <ul><li>Chuck diameter: 6"</li><li>Thickness: 2.559"</li><li>Center hole: 1.575"</li><li>Back mounting: Plain back</li><li>Bolt Circle Diameter: 5.709"</li><li>Internal Jaw Clamping Range: 0.315" - 3.149"</li><li>External Jaw Clamping Range: 1.969" -




					www.shars.com
				




The included parts are:
Chuck (202-6579) which has an advertised diameter of 6.299". The specs as displayed are for a front mounting chuck but they are still the advertised specs 





						6" 4 Jaw Independent Chuck
					

Shars Tool




					www.shars.com
				



Back plate (202-6600) which has an advertised diameter of 6.3"




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						6.3" Fully Machined Threaded Back Plate with 1-1/2" - 8 TPI for 6“ 4 Jaw Independent Lathe Chuck
					

<!--<ul><li>Mounting Thread Size: 1-1/2"-8 TPI</li><li>Bolt Circle Diameter: 5.709"</li><li>Hub Length: 0.551''</li><li>Hub Diameter: 3.583''</li><li>Flange Thickness: 0.63''</li><li>Shoulder boss: 0.157'' </li><li>No. of Bolt Holes: 4</li><li>Bolt Thru h




					www.shars.com
				




So according to the advertised specs I should have had a .001" difference in diameter when they mated up which is completely fine. In fact the difference was more like .25"

Shars will be getting a call tomorrow.


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## DavidR8 (Jan 22, 2020)

Flyinfool said:


> Since we are hobbyists we are always looking for something to make.
> How about making A cup washer that will be a very close fit to the bolts you have, and the OD a press fit into the back plate. Make the bottom thin enough so that the bolt head will not stick out the back. Once you press these into place and tighten a bolt down on it they will not move. You can then turn down the OD of the face plate. And no one will ever see what you did.


Hold the phone! I thought this was about tool acquisition...


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## extropic (Jan 22, 2020)

When I read the Shars info on the 202-6579 chuck, the drawing does not agree with the pictures. The pictures show chuck mounting holes (tapped) in the back of the chuck. The drawing shows mounting screws with heads on the face side of the chuck, (BC=5.709") indicating the backing plate is tapped. David's experience reinforces the proverb "Let the buyer beware". Good luck with that phone call.


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## savarin (Jan 22, 2020)

Its an interesting exercise making the backplate yourself and isnt really difficult.
This is the first part in making mine, mostly down the end.








						9x20 chuck backplate
					

I am considering making a new backplate for a 5" 4 jaw chuck santa has ordered for me. I have available some 2" round bar and 1" plate. (free, my price) What I would like to know is if the following process would work and be strong enough. Turn a 45 degree taper on the 2" bar, set the end of the...




					www.hobby-machinist.com
				



and these posts are how I finished it.








						aligning the holes in the back of a chuck.
					

My new 4 jaw chuck has 4 8mm fixing bolts on the back but the holes do not go all the way through so I cannot use a transfer punch. I need to transfer the hole centres on the chuck to the back plate so I can drill them.  1) How can I do this accurately?  My first thought (only one actually) is...




					www.hobby-machinist.com
				



I had only had a lathe and experience for 2 years when I did this which is why I say it wasnt difficult.
Some questions on here with really excellent answers and anything is possible.


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## DavidR8 (Jan 22, 2020)

extropic said:


> When I read the Shars info on the 202-6579 chuck, the drawing does not agree with the pictures. The pictures show chuck mounting holes (tapped) in the back of the chuck. The drawing shows mounting screws with heads on the face side of the chuck, (BC=5.709") indicating the backing plate is tapped. David's experience reinforces the proverb "Let the buyer beware". Good luck with that phone call.


I agree that the picture and drawing don't match. That said, they do sell them as a set and when I called to place the order (I can't place a web order because I'm in Canada) I asked specifically about the backplate and the chuck being 6.3" when the advertised size is 6". 
The phone person said they matched and were designed to go together.

We shall see


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## extropic (Jan 22, 2020)

DavidR8 said:


> I agree that the picture and drawing don't match. That said, they do sell them as a set and when I called to place the order (I can't place a web order because I'm in Canada) I asked specifically about the backplate and the chuck being 6.3" when the advertised size is 6".
> The phone person said they matched and were designed to go together.
> 
> We shall see



I understand (and agree). The set you ordered specifies that it includes a 202-6579 chuck. The dimension table, in the 202-6579 info, specifies the chuck is 6.299" OD. What is the measured OD of the chuck you received?


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## mickri (Jan 22, 2020)

Dumb newbie question here.  Why does it matter if the backing plate is larger or smaller than the chuck?

David  Put some mold release wax on the head and body of the screws and liberally fill the oversize hole with JB weld so that it is oozing out.   Remove the screws before the JB weld fully cures.  After full cure put the screws back in and smooth everything so there are no sharp edges.   You are done and move on to another project.

Not worth the effort to get in a pissing match with Shars.  More important things to do in life.

Just my two centovos


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## DavidR8 (Jan 23, 2020)

extropic said:


> I understand (and agree). The set you ordered specifies that it includes a 202-6579 chuck. The dimension table, in the 202-6579 info, specifies the chuck is 6.299" OD. What is the measured OD of the chuck you received?


I just mic'ed the chuck, came out at 6.311" So pretty much on spec as far as I can tell. 
So that means the backing plate  was bigger than 6.3" when it arrived.
Stymied I am.


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## DavidR8 (Jan 23, 2020)

mickri said:


> Dumb newbie question here.  Why does it matter if the backing plate is larger or smaller than the chuck?
> 
> David  Put some mold release wax on the head and body of the screws and liberally fill the oversize hole with JB weld so that it is oozing out.   Remove the screws before the JB weld fully cures.  After full cure put the screws back in and smooth everything so there are no sharp edges.   You are done and move on to another project.
> 
> ...


I totally hear what you're saying. I don't plan to get all in a fuss about it with them but they should know that their ad copy is crap


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## middle.road (Jan 23, 2020)

With the amount and number of pages they have to put together I can see how it's easy to get items crossed up.
Add to that mis-labeled items from the supplier or something getting mixed up in the warehouse.
If you were up to it I would call them again ask for 2nd tier and just casually mention that some 'learned' members up on the hobby-machinist.com forums were trying to help you figure this out because_ the through holes are for an m10 not the supplied m8s and that means that there is not proper material under the m8 mounting screw, etc, etc, etc_. 
I'd have to guess that they get a little bit of business from all of us here.
I've had to call them a couple of times over the years to straighten out messed up orders and they've always done right by me.


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## DavidR8 (Jan 23, 2020)

Looking at everything again I think the chuck specs are right. It is 6.3", it did come with M10 cap screws and the bore is 1.575.
What's perplexing is that the backing plate is larger than spec'ed and the counterbores are too large.


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## DavidR8 (Jan 30, 2020)

My earlier follow-up to this was lost in the melee.
I called Shars and spoke to Richard.
He was a very decent fellow and listened to my concerns.
There was some initial push back, that I shouldn't have turned down the diameter.
He said that the backing plate was universal and so wasn't specifically sold specifically for the 4-jaw I bought.
When I pointed out that I bought them as a package and that the backplate was/is actually described as for the 4-jaw. I also pointed out that the line drawing for the chuck didn't match the pictures but the specs did match the chuck I received.

He said he'd have to call me back.

He called me back within 15 mins and said they were sending me a new backing plate. at their expense so long as i knew there could be duty and taxes. I was fine with that.
I was expecting to get something exactly the same as the first. Imagine my surprise when I got something quite different.

Box from the first backplate:


Box for the new backplate:


The SKUs and descriptions are exactly the same.

So here's the original backplate, turned down to match the chuck:



Here's the new backplate:


The diameter measures exactly as spec'ed in the listing and is very close to the diameter of the chuck. 
Clearly something was up with the first one I received.

I'm quite happy with how this turned out. Shars and Richard in particular were totally decent to work with.

Now what should I do with the old backing plate? Collet chuck perhaps?


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## darkzero (Jan 30, 2020)

Nice!



DavidR8 said:


> Now what should I do with the old backing plate? Collet chuck perhaps?



Yep, collet chuck, mount an ER-40 plate to it. But uh... don't turn it down too much this time!  

Well I say ER collet chuck but I have only used mine like twice in the past 3 yrs or so. Mine just sits on a shelf & collects dust.


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## SLK001 (Jan 30, 2020)

DavidR8 said:


> Now what should I do with the old backing plate? Collet chuck perhaps?



Oil it then wrap it in plastic wrap and stick it on a shelf.  One day, you'll have a use for it


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## MrWhoopee (Jan 30, 2020)

Glad to hear this got resolved properly. Persistence pays.
Rather than  trying to decide now what to do with the old plate, put it aside until its purpose reveals itself.


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