# Tool post grinder



## Basil (Jan 26, 2021)

After my post on finishing crank journals for the Seal Major 30cc I got looking at grinding. I plan on putting this engine to use in a boat also I have plans to build more high performance engines so hardened steels will be required. Nothing much was popping up on Ebay and what was was in a sorry state. After a not very satisfactory result with an angle grinder I started to check out the Hemmingway tool post grinder and asked my wife to get me one for Christmas, I don't think she was planning that kind of expenditure but she agreed being totally clueless on what else to get me. Work stopped on the Seal major and I went full on with the new project. 
Casting were very good and I really think they do a great job on the blueprints. Included are a few pictures of the project. A few little deviations from the design, definitely not required but if your going to build something why not make it your own. I didn't do a very good job of documenting the build being in a rush to put the grinder to use. Fire ahead with any questions.


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## Basil (Jan 26, 2021)

More pictures. Very happy with the results. The last picture of the big end journal was with the angle grinder setup which gave a notched cut finish due to slight bearing play in the head. I did have the lathe ways covered some when I did the machining. The residue left behind is a very fine grit especially when dressing the wheel.  Definitely after witnessing this I'm going to take even more precautions going forward. Both for the machine and my health.


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## petertha (Jan 26, 2021)

Interesting. Can you elaborate on the spindle design in terms of bearing layout, like how play is adjusted out.
And how do you increment the wheel depth of cut itself? Like how fine an infeed can you make & what controls it?


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## Basil (Jan 26, 2021)

No problem Peter, I decided to take it apart again anyway to check on everything, also I had noticed some roughness in the bearing after about 30 minutes use and wondered if the pre-load was too much. A wavy washers is used to accomplish this. The inner or outer distance piece machined to determine how much this washer gets compressed.
In the rush to get the unit grinding on metal I grabbed any sealer off the shelf, not being able to put my hands on the RTV. I wanted to put something on the joint between the motor mount casting and the toolpost casting. I figured Locktite pipe sealer should work. Its was past midnight so not the brightest spark at that hour!  It did seal but something else went on and it got dragged in with the oil and deposited itself on all the races. TEFLON !
Probably didn't help not giving it enough time to properly setup.
Carb cleaner would not touch it. MEK sorted it though.
I did decided to switch over to shielded bearings with the inner oil side shield removed. £5 in bearings and a very easy fix. Smooth a silk again! Well happy and won't be doing that again any time soon!


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## petertha (Jan 26, 2021)

Thank you for the pics. 
So I take it you are in-feeding the entire grinder assembly with your cross slide? Or maybe on compound & set at high angle so you get fine depth of cut? Do you have any independent way of measuring infeed so as to feed small amounts & minimize reliance on conventional dials, backlash etc? Sorry for all the questions, I've been trying different things with my TPG. Unfortunately that beast does not play well in combination with tailstock support the way I see you are using yours.


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## Alec Ryals (Jan 27, 2021)

Basil said:


> After my post on finishing crank journals for the Seal Major 30cc I got looking at grinding. I plan on putting this engine to use in a boat also I have plans to build more high performance engines so hardened steels will be required. Nothing much was popping up on Ebay and what was was in a sorry state. After a not very satisfactory result with an angle grinder I started to check out the Hemmingway tool post grinder and asked my wife to get me one for Christmas, I don't think she was planning that kind of expenditure but she agreed being totally clueless on what else to get me. Work stopped on the Seal major and I went full on with the new project.
> Casting were very good and I really think they do a great job on the blueprints. Included are a few pictures of the project. A few little deviations from the design, definitely not required but if your going to build something why not make it your own. I didn't do a very good job of documenting the build being in a rush to put the grinder to use. Fire ahead with any questions.


Hello,
How was the finish using that wheel and grinding method ?
Thank You
Alec


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## xpylonracer (Jan 27, 2021)

Can you give some detail of the grinding wheel used please, size, grade and rpm.


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## ignator (Jan 27, 2021)

Basil said:


> No problem Peter, I decided to take it apart again anyway to check on everything, also I had noticed some roughness in the bearing after about 30 minutes use and wondered if the pre-load was too much. A wavy washers is used to accomplish this. The inner or outer distance piece machined to determine how much this washer gets compressed.
> In the rush to get the unit grinding on metal I grabbed any sealer off the shelf, not being able to put my hands on the RTV. I wanted to put something on the joint between the motor mount casting and the toolpost casting. I figured Locktite pipe sealer should work. Its was past midnight so not the brightest spark at that hour!  It did seal but something else went on and it got dragged in with the oil and deposited itself on all the races. TEFLON !
> Probably didn't help not giving it enough time to properly setup.
> Carb cleaner would not touch it. MEK sorted it though.
> I did decided to switch over to shielded bearings with the inner oil side shield removed. £5 in bearings and a very easy fix. Smooth a silk again! Well happy and won't be doing that again any time soon!


I wonder why the bearings are not of the angular contact type, with a method beyond a wavy washer to control preload.
I see you split the existing bearing outer race, I assume to show the 'munge' from the Teflon contamination.


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## Caber (Jan 27, 2021)

Judging buy the amount of blood on the castings that must have been a painful build


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## Basil (Jan 27, 2021)

Caber said:


> Judging buy the amount of blood on the castings that must have been a painful build


 Seriously! I think I'm addicted to marking out compound..


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## Basil (Jan 27, 2021)

ignator said:


> I wonder why the bearings are not of the angular contact type, with a method beyond a wavy washer to control preload.
> I see you split the existing bearing outer race, I assume to show the 'munge' from the Teflon contamination.


It looked initially like there was some flaking of the bearing race but on closer inspection it wiped off to a perfect polished finish.
I'm thinking for light duty operation it was considered adequate with standard bearings. We will see how it holds up.


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## Basil (Jan 27, 2021)

petertha said:


> Thank you for the pics.
> So I take it you are in-feeding the entire grinder assembly with your cross slide? Or maybe on compound & set at high angle so you get fine depth of cut? Do you have any independent way of measuring infeed so as to feed small amounts & minimize reliance on conventional dials, backlash etc? Sorry for all the questions, I've been trying different things with my TPG. Unfortunately that beast does not play well in combination with tailstock support the way I see you are using yours.


Yes, Just on the cross slide. I have not tried it yet with the compound. I do like the cross slide indicator. Is the block held with a stud?


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## petertha (Jan 27, 2021)

The block is pretty simple - machined from aluminum & has 2 neodium magnets glued in a recess in the base. It seems firm enough that it doesn't move under operation & makes for quick, adjustable setups. I have a 10ths indicator mounted & its really quite revealing. Just breathing on the dials or locking the carriage can move the saddle in or out 'a lot' relative to what we are probably trying to accomplish with grinding in general. If you have loose ways the needle will vibrate on either side of the actual position. Personally I'm of the opinion you need something like this for grinding unless you can count on the angled compound setting setup to make small incremental in feed equivalents. A DRO would be better but typically they are 0.0005" & still some dead band in there before the next increment lights up. That's the whole grinding issue isn't it? Making a part shiny is one thing. Hitting a target dimension to close tolerance (and still with desired surface finish) is the real challenge.


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## Basil (Jan 28, 2021)

xpylonracer said:


> Can you give some detail of the grinding wheel used please, size, grade and rpm.


These are the grinding wheels that came with the kit. 60 is the grit. RPM's of the grinder are 5,900/ 7,200 /26,200 depending on the pulley settings.
The large grinding wheel for external grinding is 3"X 0.5.


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## Basil (Jan 28, 2021)

Alec Ryals said:


> Hello,
> How was the finish using that wheel and grinding method ?
> Thank You
> Alec


Very happy with the finish. I also dressed the side of the wheel and did a great job with the finish up to a shoulder.


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## awake (Jan 28, 2021)

Caber said:


> Judging buy the amount of blood on the castings that must have been a painful build



I don't think I've ever completed a project in the shop without some blood sacrifice ...


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## petertha (Jan 28, 2021)

What is the power & rpm rating of your motor? You vary grinding wheel speed entirely through pulley/belts right? (ie. no variable speed control on the motor itself).


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## Basil (Jan 28, 2021)

No speed control . 3 speeds all by different pulley sizes. The large high speed pulley for internal grinding. 250W Approx. 3000RPM. The internal wheels are very small, about 0.6"


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## SmithDoor (Jan 29, 2021)

You use compound for just chain the angle you see durrant manual.
I upload a durrant manual he year ago 

Dave 



Basil said:


> After my post on finishing crank journals for the Seal Major 30cc I got looking at grinding. I plan on putting this engine to use in a boat also I have plans to build more high performance engines so hardened steels will be required. Nothing much was popping up on Ebay and what was was in a sorry state. After a not very satisfactory result with an angle grinder I started to check out the Hemmingway tool post grinder and asked my wife to get me one for Christmas, I don't think she was planning that kind of expenditure but she agreed being totally clueless on what else to get me. Work stopped on the Seal major and I went full on with the new project.
> Casting were very good and I really think they do a great job on the blueprints. Included are a few pictures of the project. A few little deviations from the design, definitely not required but if your going to build something why not make it your own. I didn't do a very good job of documenting the build being in a rush to put the grinder to use. Fire ahead with any questions.


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## Basil (Jan 30, 2021)

Durrant? My thinking would be just to get finer adjustment, compound set at 45deg. And grinding tapers. My Myford has some wear so is I can hold a thou. I'm very happy.


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## SmithDoor (Jan 30, 2021)

Ok it is Dumore tool post grinder 


			https://www.homemodelenginemachinist.com/attachments/dumore-44-pdf.97647/


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## Basil (Jan 31, 2021)

Ah! Very good, thank you.


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## xpylonracer (Jan 31, 2021)

I found it a pain with the compound/topslide angled at a very small number of degrees to reduce travel to get .0001" travel into the work, it is best to calculate the amount to move the saddle to compensate for the towards chuck movement when using the compound or you cut away material at the fwd end of travel but leave some at the start of the cut.
At 45 degrees it's simpler as the fwd travel is the same as in feed, guess that's a good reason to use that angle even though it's not so easy to apply a couple of tenths.


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## petertha (Jan 31, 2021)

That's what got me to making an independent dial indicator (post#5). It is direct reading of cross travel DOC increment & eliminates backlash issues & float between dovetail surfaces. Kind of like a fine reading DRO. Even so, a single increment of one tick on a tenths reading indicator = 0.0002" diameter reduction (in an ideal world with no other factors). The downside is the cross slide indicator is relatively coarse, typically 0.001" on most lathes. So each pass I back off the dial a half turn to eliminate backlash, then crept in & then only watch the needle to the dial position & locked the table. If you don't have a table lock I think grinding to any kind a tight tolerance is going to be very difficult. Even engaging the lock can easily displace the table much more than intended DOC, but this may be a function of the lathe locking mechanism. Mine just presses on the gib strip & even so I made mods to minimize unwanted secondary movement.

The angled compound is a good way to make small DOC increments because you are using geometry to your advantage. Its harder to set up an indicator but could be done. I think you would still have to obey backlash & have a predictable lock.

Regular TPGs like Dumore & Themac typically interfere with using tails stock support. Looks like the OPs arrangement works though, which is a big plus.


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## L98fiero (Feb 1, 2021)

petertha said:


> That's what got me to making an independent dial indicator (post#5).


That's a good solution and I have a similar setup but got a few used Mahr digital electronic indicators off Ebay, about 10 years ago they were around $20 but for some reason they now figure they're worth $100. These indicators measure in 50 millionths and have only +/-0.02 range but I have seen on Aliexpress indicators with 0.00004 resolution(0.001mm)/0.0002(0.005mm) accuracy for the same price but with a 25mm range. Not quite as precise but better range and with a usb port instead of a proprietary port.


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## Canyonman (Feb 1, 2021)

Hey Guys, A probably really dumb question but.......  Which way is the grinding wheel spinning in relation to the work?  Ken


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## L98fiero (Feb 1, 2021)

Canyonman said:


> Hey Guys, A probably really dumb question but.......  Which way is the grinding wheel spinning in relation to the work?  Ken


With some exceptions the wheel rotates so the nut that fastens the wheel is tightened when grinding, the sparks will go down when grinding externally and up, internally. Here is little more information Tool Post Grinder Resources | Dumore Tool Post Grinders


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## terryd (Feb 2, 2021)

Basil said:


> Durrant? My thinking would be just to get finer adjustment, compound set at 45deg. And grinding tapers. My Myford has some wear so is I can hold a thou. I'm very happy.



Hi Basil,

just for your information, by setting the compund slide angle to 84.25° i.e. an offset of 5.75° from centerline of lathe, the tool feed adjustment using the compund slide is 0.1 of the dial reading, so for a 1 thou' infeed of the cross slide the tool actually feeds in by 0.0001" or 0.0002" on the diameter that is true for all lathes, a simple trig. calculation will confirm.  Hope that is a clear explanation.







Stay safe and healthy in difficult times,

TerryD


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## Canyonman (Feb 2, 2021)

Thank You L98fiero      Ken


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## kop (Feb 3, 2021)

@terryd , Thank You! I had forgotten that one.
I'll just do this without the face-palm gif   

...last time on "Dazed and Confused in Front of a Lathe"

The sine of 5.75 degrees is .100(18806161) close enough
The sine of 30 degrees is .5 (exactly)
The sine of 45 degrees is .707(10678118) near enough

The confusion stemmed from  that one time when the cross slide dial was marked/calibrated for diameter and the compound for radius. Sorry I don't remember the machine as it was at or near high school years and I'm sure my mind was on something else.

I've been using 5.75/84.25 for decades. It's a great way to divide a bit sharper . Imagine locating coordinates on a Jig Borer in radians....

Then the infamous 30 degree (29.5) compound offset.
Okay , let's just say less than or equal to by a close order.
This is .5 exactly. This turns a compound that indicates diameter to one that indicates radius.
Even on these pages that contain such fine (and appreciated) minds I see this confused and just wrong too many times.

45 degrees is 1/2 90 or ...
Nominally useless for most of what I have or will machine.
Then again I'm an amateur radio enthusiast and .7071 comes up all the time.

@terryd , Thank You again for that synaptic connection


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## terryd (Feb 3, 2021)

kop said:


> @terryd , Thank You! I had forgotten that one.
> I'll just do this without the face-palm gif
> 
> ...last time on "Dazed and Confused in Front of a Lathe"
> ...



Hi,

You're more than welcome and thanks for your insight

TerrryD


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## ignator (Feb 5, 2021)

Back in post #5 Petertha, shows the use of an indicator which looks like tenths reading type.
A low cost digital version of this exists with a 1/2 inch travel, and with the press of a button is inch or millimeter. Resolution to 0.001mm (0.00005").
I searched for "indicator digital electronic". Careful I saw sellers showing 0.001mm indicator photos but were only 0.01mm resolution.
I purchased mine several years ago, the price has gone up. I was using my tool post grinder working on fixing the spindle taper adapter, as it was made wrong as delivered with the lathe.
With the digital indicator, I'm able to control the feed with the cross feed screw to tenths. In my case I'm using the compound slide to machine the taper of this adapter. The last pass I ground was 0.0001, and this was the first time this surface finish appeared. Sorta wood grain in appearance. I've had issues with ripples which are related to wheel balance or spindle vibration. I've increased my lathe's spindle speed to 300RPM and this fixed the ripple pattern I was seeing.
I did a high spot bluing, and I think the spindle headstock taper has some issues as well. It is seating at the top entry, and bottom, but the middle is untouched. Probably good enough. What I fixed was it was bottoming out and it would rock 0.0045 at the top. It was perplexing as it felt like it seated in the hole. But it never kept the 60 degree center that fits in this adapter centered.










						Digital Electronic Micrometer Oil-Proof 0.001mm 0-12.7mm /0.5"Indicator Gauge   | eBay
					

Find many great new & used options and get the best deals for Digital Electronic Micrometer Oil-Proof 0.001mm 0-12.7mm /0.5"Indicator Gauge  at the best online prices at eBay! Free shipping for many products!



					www.ebay.com
				



This should be available with UK or Australia eBay sites.


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## petertha (Feb 5, 2021)

Well, there is another good example of grinding with tail stock support. The motor is elevated up & out of the way & the grinding wheel is of sufficient diameter.
- what is the diameter of that wheel?
- what kind of belt is being used
- what is the power rating & what rpm

I've also wondered about the power feed on a typical import lathe while grinding. When I had a distorted feed bar I was picking up an irregular finish. That all but disappeared when the bar was straightened & other alignment fixes, all factory boo-boos. But grinding probably exaggerates this if the carriage traverse isn't also silky smooth & true. That's encouraging thanks for sharing!


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## ignator (Feb 6, 2021)

petertha said:


> Well, there is another good example of grinding with tail stock support. The motor is elevated up & out of the way & the grinding wheel is of sufficient diameter.
> - what is the diameter of that wheel?
> - what kind of belt is being used
> - what is the power rating & what rpm
> ...


The grinder I purchased new (1991) from Enco, back when they were around. They imported this machine from Czechoslovakia. So everything is metric. It is a Drukov Brno SBMT 2B. The one set of wheels for the main grinder is 150mm OD, with 50mm ID hole. I had made a hub that uses standard 1-1/4" surface grinder wheels, and I got some old used wheels that are 6 inch. I've seen this size on eBay.
There seems to be excess vibration from the motor. And it's probably running 3450 RPM, with the spindle pulley the same as the motor pulley. The belt is a flat belt, about 1-3/4" wide of some sort of nylon material impregnated with something to make is stiffer. It came with a long internal spindle adapter, and 2 smaller ones. I just found a seller in the Ukraine with 3mm and 6mm ID holes for these arbors (wheels need to be 10mm long). I need to make a longer arbor to grind the MT#4 hole true again in this adapter. You know how fun it is to measure and guess at a taper. And there does not seem to be any standards used at least relative to the 3" per foot for many surface grinder hubs. Why would they, everything is metric. I was surprised that I made a hub that fits pretty good. But maybe not, with that wood grain pattern.
The motor I think is around 1/3HP. I did have to balance the wheel. I have one of those disk type balancers. Not sensitive enough. I had gotten that this past summer. I thought of making the leveled knife edge type, but then you need to have a very level surface to set it up. And any nicks or scratches in the arbor or knife edges can give misleading results (and another project that I was not interested in). But I got it balanced enough that the ripples were reduced. The bigger thing was the lathe spindle speed of 300RPM vs the 74RPM of my lowest gear, I started with. I'm thinking the balancer's ball bearings have grease that has dried up, so I'm going to remove the shields from one side, try to degrease with starter fluid spray, and see if that improves its operation.
As for this lathe, it  is a 16x40 and weighs 5800lbs. It showed up on Grizzly's web site in 2004, never was in the catalog. I think they imported 6 of them. And from everything I've spent time fixing, it was made with every incorrectly made part that the factory used to make these scrap part machines. It does turn very true. And with good Bison and Pratt Burner chucks, the runout quality is optimum.
Peter, I did make your tool post grinder dresser. With the cantilever height off the lathe bed, I have had gouging problems, as it deflects, then recoils back. My vertical column was made with 1" round bar. The problem may be the clamp on the flat way is not rigid enough. I think with my center height this high I need one that reaches across to the other way. I like that it does not use the tail stock, and as you can see the type that would clamp on the work, would need to be a huge type clamp to fit this spindle adapter.
The number of times I had to crank the compound, which has a 5 inch travel on this lathe, was tiresome to say the least. And I typically would only grind 0.0005" per pass maximum. I learned with the surface grinder, that the expansion would cause an over feed, which after cooling would result in areas of dimples, and blacken burnt steel.


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## petertha (Feb 6, 2021)

Interesting stuff ignator thanks for your comments. I've thought about vibration too. When my motor is on I can feel the cross slide becomes 'lively' & the indicator needle does a +/- .001 dance on either side of null position on the tenths indicator. The motor itself feels smooth & balanced but I suspect some micro buzz is flowing through to the spindle because everything is hard mounted. If a motor could be divorced from the spindle, reoriented & mounted with a vibration dampening sheet of neoprene or something so its only connection to the grinding spindle was the belt, maybe that might reduce flow-through vibration & improve finish & control. That's kind of the idea in my head right now. Sourcing a motor isn't too bad, its more about making a making/sourcing a decent spindle. Plagiarized pics show general principle but replace their small grinding wheel with big wheel like yours. I have room for a motor on the far side of cross table & that takes care of TS clearance issues if the spindle is compact.

I assume you mean this wheel dresser? It was mostly orientated around scrap bin stock. The one included in the kit was a clamp on (chuck or part) affair. I don't have a (rotation) spindle lock so wasn't comfortable with any potential movement while dressing. It also never seemed to be in the right position so I came up with this which clamps on the bed. Still on my to-do list is some kind of collar under the dressing tool head so it can swivel around to different positions but still preserve the center height so the diamond remains tangent. I haven't skimmed off more than maybe 5-10 thou but seemed to work ok. Mostly its messy & I'm paranoid about grit so everything is covered. I powerfeed accross it while holding the vacuum nozzle to catch most right at source.


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## ignator (Feb 6, 2021)

petertha said:


> I assume you mean this wheel dresser? It was mostly orientated around scrap bin stock. The one included in the kit was a clamp on (chuck or part) affair. I don't have a (rotation) spindle lock so wasn't comfortable with any potential movement while dressing. It also never seemed to be in the right position so I came up with this which clamps on the bed. Still on my to-do list is some kind of collar under the dressing tool head so it can swivel around to different positions but still preserve the center height so the diamond remains tangent. I haven't skimmed off more than maybe 5-10 thou but seemed to work ok. Mostly its messy & I'm paranoid about grit so everything is covered. I powerfeed accross it while holding the vacuum nozzle to catch most right at source.


I spent the day grinding the taper of the spindle. It is very hard heat treated steel, and I only have the grinding wheel that came with the machine, some sort of gray coarse vitrified material. I need to research which kind would be good for this sort of hard steel. Then try to find one for the metric arbor.
I think I found the issue with the dressing tool. I have some geometry not quite right with the bottom side "L" clamp. It allows the plate that sits on the top of the way to flex enough.


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