Double tilt upgrade for Mk5/7

[wurlitzerwilly]

I'm about to install the Double Tilt upgrade on my 520. I've already fitted the new table posts and I've made the two wooden supports, which has now got me wondering! The main support that goes between the bench tubes and way tubes is shown on an attachment as being 12" long and a total of 5 3/4" high. It's made of two pieces, one 12" x 5" x 3/4" and one 12" x 2 1/4" x 3/4", so the 5" dimension of one piece and the 3/4" dimension of the other piece combine to give the overall height of 5 3/4".
I've made one up and checked my dimensions several times and they're as instructed. The problem I now have is that when I try to insert that support between the bench and way tubes, there's a good 1/4" clearance, which I didn't expect. I presumed that there should be almost zero clearance, in order to keep the tubes the exact same distance apart when the tie bars and the old tilt bases are removed.

Can anyone tell me whether there should be clearance, or whether I need to install some wood shims to the support?

BTW This has nothing to do with the pre-1972 versions mentioned in the instructions. Mine is much later than that.

[dusty]

I'm about to install the Double Tilt upgrade on my 520. I've already fitted the new table posts and I've made the two wooden supports, which has now got me wondering! The main support that goes between the bench tubes and way tubes is shown on an attachment as being 12" long and a total of 5 3/4" high. It's made of two pieces, one 12" x 5" x 3/4" and one 12" x 2 1/4" x 3/4", so the 5" dimension of one piece and the 3/4" dimension of the other piece combine to give the overall height of 5 3/4".
I've made one up and checked my dimensions several times and they're as instructed. The problem I now have is that when I try to insert that support between the bench and way tubes, there's a good 1/4" clearance, which I didn't expect. I presumed that there should be almost zero clearance, in order to keep the tubes the exact same distance apart when the tie bars and the old tilt bases are removed.

Can anyone tell me whether there should be clearance, or whether I need to install some wood shims to the support?

BTW This has nothing to do with the pre-1972 versions mentioned in the instructions. Mine is much later than that.

I am unable to get to the shop to measure the spacing between bench and way tubes but I have this sketch which indicates to me that the separation between those tubes is 5 3/4". Note though that this is a sketch depicting tube and shafts of a 520 but the bench and ways are the same for both.

Shaft and Tube Relationships.jpg (138.89 KiB) Viewed 963 times

[DLB]

...I presumed that there should be almost zero clearance, in order to keep the tubes the exact same distance apart when the tie bars and the old tilt bases are removed...

Full disclosure, I didn't do my upgrade as described in the manual. I just went to the shop and measured a DT machine and a traditional machine and both measured ~5-7/8". I would not think it is critical to have zero clearance, but nothing wrong with shimming if you are more comfortable. The new hardware will re-establish the correct dimensions.

My machine was very light, the headstock was off for PowerPro upgrade and the table was off. So I just used a scrap of a beam to keep the tubes from running into each other, I couldn't guess the dimensions. I put a sawhorse under one end, upgraded, then did the other end. IIRC I started at the Headrest end. I did not turn the machine upside down.

- David

[edma194]

I have to tighten up my recently acquired double tilt carriage. I have only skimmed the installation instructions so far.

What is the purpose of these special boards? The way tubes are locked in the tilt ends with set screws. Is there some way the entire assembly is not essentially self aligning as with the regular tilt? I realize there is no special special adjustment screw like the normal left end base. Is this the issue, the aligning the way tubes?

[chapmanruss]

Since the support is to keep the spacing between the bench and way tubes adjust it to that spacing. Don't make it to snug so there is a bit of play left to get the new ends on.

Sorry I cannot tell you how that went for me when I did my Double Tilt Upgrade. Because I was doing the Power Pro Headstock Upgrade at the same time, I had the bench completely apart and other assemblies removed. Did touch up painting, removed the original Headstock and replaced it with the still in progress Power Pro DIY upgrade so it was like building a Mark 7 from the ground up.

[wurlitzerwilly]

I am unable to get to the shop to measure the spacing between bench and way tubes but I have this sketch which indicates to me that the separation between those tubes is 5 3/4". Note though that this is a sketch depicting tube and shafts of a 520 but the bench and ways are the same for both.

Shaft and Tube Relationships.jpg

Thanks Dusty. Your dimensions help to confirm some of my findings.

I did get out to the shop today and I think I may have sorted out my confusion.

Your dimensions and my support instructions both confirm that the height between the two sets of tubes should be 5 3/4" but that's only when fitted to the new tilt bases, which of course is my ultimate objective.

However, those dimensions are not the same on my unconverted 520. In fact it seems to be all over the place. The heights compared to 5 3/4" vary by as much as 1/2" from extreme left to extreme right and from front to back. ISTR that when I fitted the PowerPro into the old headstock, there was an adjustment which would change the tube relationship by rotating the Way Tubes. This may account for the discrepancy.

Ultimately, I guess this doesn't matter as the dimensions will be correct when the new bases are installed. I've checked the bases with callipers and they're spot on. Looking at the way the headstock currently sits, even lowering it by up to 1/2" would not cause it to foul the Way Tubes, due to the sloped of the lower casework.

My only concern is that when I install the first base, the other end of the tubes will still be in the old base at the old dimensions, which could cause distortion at the end of the tubes, as they would slope towards the new base. I'm hoping that if the retaining screws in the original base are loosened first, there will be enough tolerance to allow the tubes to "bend" without actually bending at the ends.

[wurlitzerwilly]

Full disclosure, I didn't do my upgrade as described in the manual. I just went to the shop and measured a DT machine and a traditional machine and both measured ~5-7/8". I would not think it is critical to have zero clearance, but nothing wrong with shimming if you are more comfortable. The new hardware will re-establish the correct dimensions.

My machine was very light, the headstock was off for PowerPro upgrade and the table was off. So I just used a scrap of a beam to keep the tubes from running into each other, I couldn't guess the dimensions. I put a sawhorse under one end, upgraded, then did the other end. IIRC I started at the Headrest end. I did not turn the machine upside down.

- David

Hi David. I did consider fitting the upgrade bases, without turning the machine over, but ISTM that would only work if the headstock was removed, like you did. I don't really want to do that again, so I'm committed to following the original instructions.

Thanks for your comments though. It all adds to the overall picture and knowledge pool.

Alan

[wurlitzerwilly]

Since the support is to keep the spacing between the bench and way tubes adjust it to that spacing. Don't make it to snug so there is a bit of play left to get the new ends on.

Sorry I cannot tell you how that went for me when I did my Double Tilt Upgrade. Because I was doing the Power Pro Headstock Upgrade at the same time, I had the bench completely apart and other assemblies removed. Did touch up painting, removed the original Headstock and replaced it with the still in progress Power Pro DIY upgrade so it was like building a Mark 7 from the ground up.

Yeah, you wouldn't want that support too tight, it would make it very difficult to fit the tubes in the new bases.

If I find the support too tight, I'll just sand a little off the top, as I have a separate belt sander.

[wurlitzerwilly]

I have to tighten up my recently acquired double tilt carriage. I have only skimmed the installation instructions so far.

What is the purpose of these special boards? The way tubes are locked in the tilt ends with set screws. Is there some way the entire assembly is not essentially self aligning as with the regular tilt? I realize there is no special special adjustment screw like the normal left end base. Is this the issue, the aligning the way tubes?

The way I see it is that the support that holds the tubes apart is there to prevent the end of the tubes sagging where they're still attached to the original base at one end. Without support their natural weight could cause the attached end to distort. Of course I may have the concept totally wrong in my head and the support is just an alignment tool. The jury's out.

The other support is just a square of 3/4" lumber that shims the headstock off the floor when the machine's inverted, so that the total weight is shared between the headstock and the table.