Tray
Aluminum
- Joined
- Jul 22, 2009
- Location
- Southampton UK
I originally posted some details about this grinder on the Abrasive machining thread and got some good advice from the guys there including Michiganbuck.
https://www.practicalmachinist.com/vb/abrasive-machining/harbots-leicester-surface-grinder-351643/
I seems this machine is fairly rare (I know that does not mean good nor valuable) given that I have not found any information about it, but it seems to follow fairly standard design practise. The ways are arranged as follows; traverse (X?) one inverted V and a flat, back to front (Y?) two inverted V's, Spindle rise & fall (Z?) two front flats with two more at the rear, a flat gib to take up play in the X plane. No gib in the Y plane; this seems to rely on the torque applied to 4 caps screws that hold a large plate to the back ways.
The machine was very dirty and dry so I did not feel it was wise to move any of the axes too much to check for wear. As I said in the other thread the machine doesn't owe me much.
Now I have the Z axis apart I'm looking for guidance; I have cleaned up and rewired an M250 Lathe and a Taiwanese BP clone and replaced parts but have no rebuilding / scaping experience. I appreciate that I will need to acquire some tools and some skills If I am to rebuild it. Being able to scrape will come in useful for new build projects.
I have had an initial look at the Z ways, they are approx. 22" long and approx. 10"� apart. With a borrowed 18" �straight knife type edge (I know, too short) I can see there is wear on the front faces of the front ways but I could not get a 0.002"� feeler gauge in the gaps. The sides of the front ways don't look as bad. Back ways are hard to see.
If I were to want to try to recondition these ways it looks like I could take the column off the base as there are four machine screws accessed from the back of the machine and two dowels which look like they were installed from the front at an angle; I'm concerned that if they are at different angles to each other I may run into trouble, I don't know if the can be punched though. Clearly I'll need to borrow a hoist to lift it off and set it on the surface plate each time I need to take a rub.
It's not surprising those ways are worn given the amount of congealed oil / grinding residue that was filling the oil grooves and generally under the ways.
I'm thinking I will need a surface plate 24"� long and at least 18"� wide. What do folks think about this one?
Rotagrip - Black Granite Surface Plate 24 x 18 x 3in With Ledges
Are the ledges more trouble that they are worth ? and Is an AA grade Ok in a workshop where the temperature fluctuates. There are used plates on auction sites (mostly CI) but they seem to be pricey given that their surfaces look less than pristine and their accuracy is undetermined.
In other Z axis news the feed screw is ¾ x 10 V form and noticeably worn in comparison to a thread gauge. I seems I can get an ACME replacement from Roton the US far easier and cheaper than in the UK. At $13 a ft and $40 for the nut it's not worth me trying to machine them. Can anyone see a downside to going from V form to ACME ?
Thanks in advance
https://www.practicalmachinist.com/vb/abrasive-machining/harbots-leicester-surface-grinder-351643/
I seems this machine is fairly rare (I know that does not mean good nor valuable) given that I have not found any information about it, but it seems to follow fairly standard design practise. The ways are arranged as follows; traverse (X?) one inverted V and a flat, back to front (Y?) two inverted V's, Spindle rise & fall (Z?) two front flats with two more at the rear, a flat gib to take up play in the X plane. No gib in the Y plane; this seems to rely on the torque applied to 4 caps screws that hold a large plate to the back ways.
The machine was very dirty and dry so I did not feel it was wise to move any of the axes too much to check for wear. As I said in the other thread the machine doesn't owe me much.
Now I have the Z axis apart I'm looking for guidance; I have cleaned up and rewired an M250 Lathe and a Taiwanese BP clone and replaced parts but have no rebuilding / scaping experience. I appreciate that I will need to acquire some tools and some skills If I am to rebuild it. Being able to scrape will come in useful for new build projects.
I have had an initial look at the Z ways, they are approx. 22" long and approx. 10"� apart. With a borrowed 18" �straight knife type edge (I know, too short) I can see there is wear on the front faces of the front ways but I could not get a 0.002"� feeler gauge in the gaps. The sides of the front ways don't look as bad. Back ways are hard to see.
If I were to want to try to recondition these ways it looks like I could take the column off the base as there are four machine screws accessed from the back of the machine and two dowels which look like they were installed from the front at an angle; I'm concerned that if they are at different angles to each other I may run into trouble, I don't know if the can be punched though. Clearly I'll need to borrow a hoist to lift it off and set it on the surface plate each time I need to take a rub.
It's not surprising those ways are worn given the amount of congealed oil / grinding residue that was filling the oil grooves and generally under the ways.
I'm thinking I will need a surface plate 24"� long and at least 18"� wide. What do folks think about this one?
Rotagrip - Black Granite Surface Plate 24 x 18 x 3in With Ledges
Are the ledges more trouble that they are worth ? and Is an AA grade Ok in a workshop where the temperature fluctuates. There are used plates on auction sites (mostly CI) but they seem to be pricey given that their surfaces look less than pristine and their accuracy is undetermined.
In other Z axis news the feed screw is ¾ x 10 V form and noticeably worn in comparison to a thread gauge. I seems I can get an ACME replacement from Roton the US far easier and cheaper than in the UK. At $13 a ft and $40 for the nut it's not worth me trying to machine them. Can anyone see a downside to going from V form to ACME ?
Thanks in advance