LV steel lapping plate too hard?

[CHJ]

There is no way you are going to get diamond 'grit' to embed in a hard steel plate and stay there, at best you will just achieve a frosted surface on the steel, the diamond particles will just drop or wash off as soon as any disturbance is presented.

At best they will be sat in a depression about 100th of their 'diameter', manufactures of diamond plates have considerable difficulty in forming a plated layer (nickel ?) with enough depth to retain the 'shoulder' of the particles.

Think in terms of how a stone is retained in jewelry such as a broach or a ring with claws, something achieving similar is required, failure to achieve this successfully is the reason cheap diamond plates 'wear out' rapidly.

 

[ali27]

There is no way you are going to get diamond 'grit' to embed in a hard steel plate and stay there, at best you will just achieve a frosted surface on the steel, the diamond particles will just drop or wash off as soon as any disturbance is presented.

At best they will be sat in a depression about 100th of their 'diameter', manufactures of diamond plates have considerable difficulty in forming a plated layer (nickel ?) with enough depth to retain the 'shoulder' of the particles.

Think in terms of how a stone is retained in jewelry such as a broach or a ring with claws, something achieving similar is required, failure to achieve this successfully is the reason cheap diamond plates 'wear out' rapidly.

I have seen diamond lapping plates which have the diamonds sintered in them. Obviously I
would not be able to do that as well, but from my experience silicone carbide embeds quite
easy in soft steel. Diamond is much harder than SiC and should embed even easier.

This gives some more info:
http://www.ehow.com/how_11401951_charge ... spray.html

Ali

 

[GazPal]

from my experience silicone carbide embeds quite easy in soft steel. Diamond is much harder than SiC and should embed even easier. Ali

Perhaps the above answers the original question by recognising a softer plate is best suited to embedding grits of various grades. Depending on your regime, why not invest in some mild steel plate, have it milled true and use a section slab for each grit being used? The hardened plate you've bought doesn't seem to match your chosen mode of lapping.

 

[Harbo]

I've used a sheet of Acrylic - it holds the grit very well.
And much cheaper too?

Rod

 

[James C]

I've used a sheet of Acrylic - it holds the grit very well.
And much cheaper too?

Rod

Garrett Hack makes the same point about using hard level plastic in his Handplane book. I was suspect but glad to hear it works as I have a couple of sheets of spare acrylic. What thickness do you use and what is it mounted on?

 

[Harbo]

I think my stuff is about 5mm.
I just place it on a piece of old kitchen worktop.

Rod

 

[James C]

Sounds good I might have to check with management to see if we have funding for some SiC powder.

 

[ali27]

from my experience silicone carbide embeds quite easy in soft steel. Diamond is much harder than SiC and should embed even easier. Ali

Perhaps the above answers the original question by recognising a softer plate is best suited to embedding grits of various grades. Depending on your regime, why not invest in some mild steel plate, have it milled true and use a section slab for each grit being used? The hardened plate you've bought doesn't seem to match your chosen mode of lapping.

Gazpal, your response makes sense. I am a bit confused because supposedly the
LV plate is soft steel. So lets say I buy mild steel and it turns out too hard again!
What hardness do I need? What specifically should I ask for?

Are mild steel and cast iron the same? Cause I think I need cast iron.

Anybody knows where I can get soft steel ground flat for a nice price? I think
buying a bigger plate might be a good idea. I could use it for flattening my no6
and perhaps a no7 in the future.

Is it possible to get a lapping plate that does not corrode?

Thanks again guys.

 

[GazPal]

from my experience silicone carbide embeds quite easy in soft steel. Diamond is much harder than SiC and should embed even easier. Ali

Perhaps the above answers the original question by recognising a softer plate is best suited to embedding grits of various grades. Depending on your regime, why not invest in some mild steel plate, have it milled true and use a section slab for each grit being used? The hardened plate you've bought doesn't seem to match your chosen mode of lapping.

Gazpal, your response makes sense. I am a bit confused because supposedly the
LV plate is soft steel. So lets say I buy mild steel and it turns out too hard again!
What hardness do I need? What specifically should I ask for?

Are mild steel and cast iron the same? Cause I think I need cast iron.

Anybody knows where I can get soft steel ground flat for a nice price? I think
buying a bigger plate might be a good idea. I could use it for flattening my no6
and perhaps a no7 in the future.

Is it possible to get a lapping plate that does not corrode?

Thanks again guys.

From my basic understanding, mild steel (Low - Medium carbon content) tends to be softer than cast iron (Very high carbon content) and tool steel (High carbon content) but each can be in an annealed state when supplied or (if hardened) tempered to draw/reduce it's hardness. The hardening and tempering process and characteristics of a metal are key to how well suited it is to the task in hand.

The engineers and metalworkers here are - by far - the best sources of advice on this topic, but I think supply and machining would be best handled via a local small engineering company with suitable milling facilities. Most carry suitable metal, whilst pre and post machining heat treatment can also be handled locally and sourced once in-roads have been made with the engineering element.